traduction en anglais

About the skirt line, it's a little different from "wearing skirts is pointless," it's closer to "because i can't wear something like a skirt (sukaato nante)" from the verb "haku,' so i'd go with something like "I won't wear something like skirts/a skirt anymore"
You're right about the "favorite pink" portion, but just btw, the two kanji there represent to 'seal,' so it'd be more like "I'll seal away even (cuz もcan mean 'even' as well as 'too,' could be either) my favorite pink."
5 is a little hard, cuz amanojaku is something like "weakness of heaven," so it means contrary efforts here
11 is deai or encounter/meeting plus machigai or mistake in the presumptive form, so "if our meeting was wrong/mistaken, difficult days.. (will come is implied here)
12 includes the ji character from jibun or self, plus the kanji for abuse, so it's "self-deprecating" plus doryouku or "effort/hard work", and bakkari means only but with a negative connotation, and chau ending indicates passive voice "end up doing x", so it's more like "i end up making such self-deprecating efforts
15 is more like "like a fish in a trap," but yeah, "caught by his nature before knowing it" is very well done!
16 might be referring to if the woman makes up her mind, the man will be no match, given, cuz it's onna ni kanawan so can't win on/against (in this case "over") a woman
for 17, I think it's more likely the girl is referring to the guy being "entranced" (literally naka or inside + yume or dream) by another girl "from first sight", because it starts with her referring to the subject "person i love"
18's a bit more involved, because kureba is give, so the compound verb laugh/smile+give means "give me a smile"
final line'd be like "as long as you smile for me" + "say clown-like things" which you've already got down well
And for line 20, it's about wanting to "be your happiness," or more figuratively "make you happy," rather than staying by their side like the previous chorus.
it's a very fun song, and i think you translated the bridge (hard part) really well!