Sakura Saku - Oneshot

[MangaDex]

 

[Nosebleed]

似合わねー is just a casual 似合わない, having a ー is just elongating the last vowel (to get closer to the original ない), it doesn't do anything semantically here.
It's clearly negative, especially given the context (how the other character reacts negatively to it). Not sure what the people that you saw translate it differently were on.

 

[Lyah-w]

I see, thanks!

 

[Maid_kun]

cute,
I hope she lives a happy life.
free from any nay sayers denying her life as a girl.

 

[nueee]

Thank you!