Just tried to transcribe this dialogue to analyze a bit the kanji in the charakter names and try to catch the different way of speaking of each one. Feel free to correct me on the transcript or translation - any help is very welcome. Thanks a lot.
松浦 果南 「よくわかったね?」“We understand each other well, eh?”
高海 千歌 「なんとなくね?」 “Something happened, no?”
渡辺 曜 「待ってたよ。」“I was waiting, you know!”
国木田 花丸 「お芋焼けたずら!」“I burnt a potato” (I am not sure about this one, buy Hanamaru was seen grilling a sweet potato earlier in the clip…)
桜内 梨子 「いい曲ができたよ。」“I finished a good song!”
黒澤 ルビイ 「練習もバッチリです!」“The training is perfect!”
津島 善子 「全てのリトルデーモンのコードはお身と品のよ。」“All the little demon’s codes are yours with body and soul” (… or someting like that?)
黒澤 ダイヤ 「生徒会の仕事もたっぷりありますわよ。」“There is plenty of student’s council work you know.” (question: how common is わよ in reality. I think to have heard only わね (so the ‘feminine’ わ replacing he ‘masculine’ よ…)
小原 鞠莉 「一緒に帰るです!」“Let’s go home together!” (is this even grammatical or a “is joke! shiny” as Mari would say?
よく well
わかった understood/to be found out/to be known
I think here she’s referring to the fact that Chika was waiting for her when she arrived?
She knew when/where she was arriving, or that she knew she was arriving at all.
Some context would be useful here, but that’s probably it.
なんとなく somehow or other, for some reason or another, without knowing why
Very.
I don’t know about all that , but it’s not grammatically correct. You can put です after some words, but usually not verbs.
Ah, I see that she sounds foreign, or just exaggerated.
Is it not this?
お見通し
seeing through (a trick, someone’s mind, etc.)
You can also hear she says おみとおし なのよ instead of しな, though weird inflections exist.
Some context would be useful here, but that’s probably it
yes , that is it I think (the full video is about them being connected and how her friends just feel they should pick her up from the station)
なんとなく somehow or other, for some reason or another, without knowing why
Of course, not sure where I got the “happened” from. I think she is referring that she felt she should show up at the station for no particular reason?
Ah, I see that she sounds foreign, or just exaggerated.
She is both, yes… That is why I assumed her using the dictionary form of the verb with です is just for comedy effect possibly, thanks for confirming.
Is it not this?
お見通し
seeing through (a trick, someone’s mind, etc.)
You can also hear she says おみとおし なのよ instead of しな, though weird inflections exist.
Is little demon what she calls Kanan?
An yes, she calls all of her friends リトルデーモン in general . With the word you found it makes a lot of sense yes, thanks for pointing it out!
grammatically it is still puzzling me though… 「しな」would be then the negative imperative (like 勉強しな - don’t study). のよ like \reinforced question’ maybe.
“Hey, now don’t see right through all the little demon’s code?”
Given her facial expression and the context of welcoming Kanan back, I’d say it’s more like “I roasted a potato [for you]”
Oh, yes that is it! That way it makes much more sense why she would say it in that moment. You are nicer person than I am, it did not occur to me the potato might have been for Kanan
thanks for the idea that コード the “chord”
“Seeing through all the little demon’s chord” might then mean like being able to tell their voices apart when all nine sing together - understand their connection, etc.
I think it’s 行動 (こうどう). Makes sense in the context as well („seeing through all their actions/behavior“)
= „The actions of the little demons are predictable / I predicted them correctly / I saw right through them“
thanks @morteASD and @Myria I indeed have trouble remembering which is which I will work harder on it!
I learned so much from you and also before @Kazzeon and @Belthazar, sinceI posted this! this forum is a really cool place to hang out at. I hope I can give some back at some time giving advice to newer people!
(LexiJ gains 24 XP and learns a new attack "Create Topic")
, but it’s not grammatically correct. You can put です after some words, but usually not verbs.
, that is it I think (the full video is about them being connected and how her friends just feel they should pick her up from the station)
. With the word you found it makes a lot of sense yes, thanks for pointing it out! 
true… 行動… sometimes the obvious is not very obvious, obviously
I will work harder on it!
from you and also before