Finished my chores! I had time to follow the link that you provided:
I like this very much. It jibes with my feeling that somehow English “senryu” with 5-7-5 syllables don’t quite capture the vibe (nor difficulty) of their Japanese equivalents.
From here on out, I will award slightly more weighting to “short - long - short” English translations, on a graded scale:
Baseline: an understandable translation that captures the gist of the original. As described previously, I will grade short and pithy submissions with more likes and fewer introduced words the highest.
5-7-5 gets slightly more weighting than just a straight translation
4-5-4 gets slightly more weighting than 5-7-5
3-5-3 gets slightly more weighting than 4-5-4
Syllables will be counted using the How Many Syllables website. They at least claim to have been cited by the MLA, APA, and (my favorite) the Chicago Manual of Style, which is canonical enough for me. More importantly, I can just plug in a word to get a single, independent count without thinking.
No idea what’s correct grammatically, but I’ve been practicing 謙譲語・尊敬語 so I tried to keigo-ify it (in the like max-敬意 way and not just the 丁寧語 if you know what I mean)
But I’m also bad at that so don’t trust me or anything
Attempt
こんにちは！ Rexと申します。アメリカ人でございます。
こんな片言の日本語しかできないので（/は？）申し訳ございません。
(I thought this was 致しかねます for a moment but that’s actually for not being able to do things.)
二、三年前から漢字を一所懸命勉強いたしております。数十年前から少し日本語を（で？）お話しいたしておりましたけれども（、wanikani.com と言うWEBサイトのお陰でやっとすこし書ける、読めるようになりました。
Note: Whether or not いたしております is 二重敬語 or an acceptable saying is apparently somewhat up for debate?
I couldn’t find any special 敬語 for できるようになる so I assume there isn’t any, but I could be wrong
偶然、そのサイトのフォーラムで川柳の話がでてきました。(Just in 丁寧語 is good I think since you aren’t the one doing it)
（名前）さんの「名作川柳」ページを見つけさせていただきました。(I looked it up and apparently it’s only 丁寧 if you contort 見つける into a different expression? Idk just I kept coming across “見つけるの敬語はない”) 凄く（とても？）ありがたいです！（although an article said that ありがたい might make someone feel 不快 (idk why tho) so maybe an expression like 心より感謝申し上げます) 面白いし短いですから外人(maybe 外国人? I’ve heard some foreigners find 外人 rude)に対して完璧な練習になりました。
この数週間でフォーラムの友達と川柳の翻訳を毎日一つずつ頑張っています（おります？）。ちょうど一年ぐらい掛かると存じますが、もう1ヶ月分が出来ました。
(Also “appreciate” how I misconstrued 川柳 as a name for a good while)
許可なんか（なんか is a bit critical? Maybe のようなものは or just は・が）頼んでいなくて大変失礼かも知れません。でも（しかし？でも is kinda 話し言葉 and apparently しかし is more business scene）興味（が？）あれば今までの英語版川柳はここでございます：
毎日このspreadsheet（スプレッドシート？）をupdate（アップデート？）いたします。間違いが多いかも知れません。英語バージョン（版？for consistency) はほとんど５−７−５ルール（が守られていません？）が大体同じ気持ち（印象？感じ？ → maybe not wrong necessarily but you might want to check if 気持ち is the right form of “feeling” here）になったと希望しております。
(Let us briefly appreciate that the internet has an entire article dedicated to telling us that the 敬語 of かもしれない is かもしれません, complete with a fair number of stock photos of smiling businessmen.)
spreadsheetはパブリック（一般公開？is the phrasing used on the Google Sheets website) ですがそのリンクがないと見つけられません。フォーラムの話はプライベートです。
こうさくにシャネルのあきばここにもたせ
A 4-5-4 attempt:
Let the kid use / the Chanel carton / for handicrafts
The 川柳 humor is hard to get on this one. Allusion to parents’ vicarious ostentation at kid’s school (in the handicrafts class or something)?
And also, is 空き箱子に持たせ the poetic version of 空き箱を子に持たせ?
Here are the links to the 356 Japanese originals (spoiler free) and to the the spreadsheet with all the upcoming senryu as well as the translations to date.
I’m probably wrong, but I think it means giving the empty box “as a gift”. That is, 持たせ is a noun meaning gift or “given-thing” (per the weblio link I gave earlier).
So I think the に functions as “to” here. Giving a gift to the child.
(Ignore what I wrote before the edit – I’m just back from the gym and blood apparently hasn’t started flowing to my brain again yet).
Coffee has kicked in. This is exactly what you wrote, of course! Reading too quickly I thought you’d replaced the に with を, not added the missing を.
I try to write my Japanese emails pretty much the same way I’d speak if I ran into the gentleman on the street: polite but informal and friendly.
尊敬語 is a tricky thing for even natives to pull off correctly. I know I’d definitely sound stilted, weird, and plain wrong if I tried to use too many honorifics.
Its worth studying for sure, but for someone at my level I think it’s more important to understand it when I hear or read it than it is to attempt to use it when speaking or writing, especially something as informal as an email. I believe a foreigner will be forgiven for slightly insufficient politeness, but overly obsequious and flowery wording will sound quite grating very quickly, especially if there are any mistakes (I make lots of mistakes ).
I’m reasonably confident that he will at least get the gist of what I was trying to say.
Responses to your specific suggestions
I don’t actually know his name, just his email address! This made the salutation pretty difficult. Hence the simple こんにちは.
This might have been better, dunno.
I think the most important part of sounding polite in Japanese is to humble yourself and your family/cohorts/company, and to honor the person you’re speaking to and anyone related to them. In this case, I’m one of the gaijin so I think it’s okay to be direct.
This seems to be the single hardest thing for westerners visiting Japan, by the way: e.g. drop the さん when speaking about yourself or anyone in your group. We’re trained to apply Mr./Mrs. indiscriminately and tend to just think “polite mode” / “direct mode”, using the same mode for everything.
Because Japanese culture is so outward, お客様 oriented, it can cause discomfort to even imply any sort of debt or obligation indirectly — even an expression of gratitude can imply a debt! (This makes sales in Japanese a particularly interesting challenge, by the way.)
In this case, I was just trying to say how grateful we were for finding the list. It was the first way I thought of to say it. After pulling out my dictionary, I see there is also 忝い but it is less common.
This was the only sentence I struggled with. I wanted to recognize that we hadn’t asked for permission to use his list, but I know for certain he’s not the author of them either and was unlikely to have asked for permission to use any of them himself. I expressly wanted to tread lightly and keep it informal/conversational, so used なんか instead of など、とか、のような etc.
Doubtless, there was a better way to say it, but I wanted to move off of that sentence quickly!
Yeah, I got tired fighting with my IME. Entering カタカナ語 is the worst!
I’ve honestly no idea what’s better, but we’re talking senryu not haiku or anything terribly formal so I think it’s fine to keep it simple
Probably what I sound like whenever I try to communicate ngl
But I feel guilty whenever the person I’m talking to responds super politely and I’m not even though I feel like I’m “below” them, so I try to do it (It’s kinda something I do in English, too? Like being super polite to people from school in emails. Sometimes I think it’s why people give me A’s even though I’m a jerk who never shows up)
Bro you should see the book I have on it (敬語サクッとノート). There are so many weird things that I would never think to consider (like complimenting your boss is apparently taboo)
That makes sense I guess. Although you never know when the person you’re talking to is also 外国人
Probably hard for Japanese people, too. There was like a whole section in the book for making sure to address your mother non-politely (+ your boss when talking out of company) and to not use 亡くなった for the death of your dog or your grandmother
Lol it sounds like a culture where everyone has PDA. I’ll have to keep that in mind since over here the more thank yous you give the better
Do you use Windows?
At least on MacOS, you can put anything into katakana by going ↓↑↑ on your keyboard (or holding shift). I think the shift (or maybe caps lock) also works on Windows
I thought it was more kinda a negative thing? Like not just inconsequential more “I don’t like it and it’s pointless/worthless so I don’t care” (like here)
Is there a chance you’re both right?
I’m wondering if it’s like the way in English we can use “it doesn’t matter” to be both literal like @Rrwrex is saying, and defeatist/negative like @GearAid is saying.
There’s at least an equal chance that we’re both wrong.
In this case, the author has already expressed negative feelings (ヤな) about the matter. I believe the last part of the sentence means they don’t care how the matter is resolved: any way is good. In English, I’d express that as being something not worth worrying about.
goes to 
This made the salutation pretty difficult. Hence the simple こんにちは.
