The issue I see here is that both of those suggestions would require a complete re-working of the item pages. The pages simply aren’t set up with the features required to have selectively visible text. Furthermore, since the sentences have grammatical elements alongside the vocabulary items, each unit would need to be identified manually.
Would this be useful? To some people, maybe.
Would this be worth the time and effort? I’d argue no.
Compared to the number of other things the Tofugu team have to work on, this would be a poor time investment. WaniKani is a Kanji learning platform and isn’t here to teach grammar or sentence structure. The sentences, that were manually written out for over 6000 items, are just there to allow you to see the items in context. If you want to see how the sentences are structured, use an external parser like ichi.moe
even if I try to translate it sometimes, when I see the translation right below, it usually has nothing to do with what I had translated “out of nowhere” appear words in the english translation made by WK.
^ This. Also, once you reach basic grammatical fluency, most of the example sentences aren’t that hard to digest, sometimes you need to look up a few words, true, but that takes a few second / word at most, so I don’t see the benefit for most users. It’s also a good exercise I think, as in the wild you also won’t know every word.
Though IF the Tofugu team ever finds themselves with nothing else to do anymore, I don’t think your suggestions are bad, it’s just that the amount of work required vs the pay-off is quite unbalanced.