Honorifics are always important imo it ticks me off so much when translators just do away with them bc it tells you so much about the relationship between characters. The worst is when like onii/onee-chan is translated to big bro/sis it feels so unnatural literally no one calls their siblings bro or sis in English regularly.
I've seen it argued it makes it more approachable for new readers, but I'd argue having an explanation page at the beginning makes much more sense. What's really bad is when they switch to using mrs. and mr.
Then there are manga like "sometimes even reality is a lie" where the honorifics are a plot point.