Useful items

I don't actually have stuff by these bands, so I went from your notes where you had questions/comments/kanji that I could verify.

zakuro ai

I couldn't find tsugaibina, probably because it's "tsugai hina" or "a pair of dolls". Nelson's defines that hina as "chick, squab, duckling, doll", the last of which is the commonest usage. The other hina (different kanji) is "lowliness".


Danzetsu

Danzetsu is "severance", and according ot the Kojien has to do with severing ties. Death may be an extension of the meaning, but certainly not the basic meaning.


Mucc Stuff

Shiawase no shuuchaku

Shuuchaku is "the act of arriving at the end" (最後に執着すること), but if you think it should be the other shuuchaku 執着, a better translation is "fixation".



Kimi ni sachi are

"are" is an emphatic, os "For you, there is happiness" It's a form often used in kotowaza, so it needs that same sort of strong proverb sense in English. "Here is" isn't grammatically correct translation.

uso de yugamu shinzou

For the title to be "distorted" (in the past), it would have to be "yuganda". Yugamu has to be the present or the future, so you may want to change the tense. To be graamatically fair, even if you can't change the tense, it should be "a heart which is distorted by lies". Mushing up relative clauses will cause you a lot of trouble when you do more complicated translation.

Swim! Taiyaki-kun

Your explanation of "kun" is inaccurate. Taiyaki-kun wouldn't be translatable to "Mr. Taiyaki", because, like "chan" it's used to refer to children or intimates. There is no direct translation for it as such. You got the pun, and to add to that, a taiyaki is shaped like a bream (it's a common fish in Japan, IIRC) and fuilled with red bean oaste (an).


Mae e

I'd say "Forward", or "To the front", especially since "mae ni" (the same as "mae e", means "ahead" or "before", but it's largely semantics.


Kaeranu hito

I'm going to venture a guess that the kaeranu is 帰らぬ, (or kikoku no ki if the Japanese doesn't display) and therefore, rather than "come back", I would use "return" for the sake of accuracy.


Zutazuta

I'd prefer a stronger term, like "Shredded", largely because of the tone you set in the song itself, and to avoid the Natalie Imbruglia reference.

Keep at it. Practice makes closer to perfect, in that inexact science we call translation.