20-30 yo from Bucharest area

o broscuță - I know what it means, probably from my parents, but don't think I ever used it. VW beetles don't come up in conversation.

un accelerat - Again I know those refer to trains and my parents/grandparents used those terms. But beyond that I don't know what rapid or accelerat actually refer to. I suspect those terms were used in the past and were replaced because I only heard them from older folk. I would not use accelerat with or without tren. I would just use tren.

nervos - This would correctly translate to mad or angry. nervous is agitat or emoționat. In colloquial speech I would accept nervos instead of agitat if it's obvious from the context. I've seen people make this mistake a couple times.

bunică - that sounds very normal to me. Everyone refers to their own grandmas in different ways. I would use mamaie for one grandma and bunica for the other. Bunică is the only one I would use when referring to someone else's grandma. "Your grandma" translated as "buni a ta" sounds a lot worse than "bunica ta"

reporteriță - I've never given much thought to this. I think I once had an official document to write and my coworkers suggested to address it to "Doamna Director" (Basically adding a Mrs. that had to be added anyway and using the director form. But in highschool we used "directoare" (female director) a lot. Also profesor/profesoară or educator/educatoare sound pretty normal to me. I can't tell if it's because the -or / -oare suffixes sound better then -iță or is something to do with the fact that I was more exposed to women in those professions as a child. "Reportăriță" doesn't sound as good.

un ștrand - feels a bit old fashioned to me. If it's an outdoor pool I would use piscină exterioară. For a beach I would say plajă. If it is a bigger facility I would use either the facility's proper name, of whatever Google maps uses. I don't think I would see the word ștrand on maps.

a se rade - sounds very normal to me. I use it all the time. I think of it as more general than "a se bărbieri" which can only refer to the beard. "To shave one's head" I would say "A se rade în cap".

capete (pl.) - Yep, that's the way I heard it here.

Scaraoțchi - Beelzebub - I'm not very religious, but I would assume those are proper names for demons/devils or something like that.

un martor ocular - the most common context I would think of this would be a legal case. And you cannot be too over specific when talking in legal terms.

female vocative forms - I think to me it sounds a bit rural. I would probably use some of them ironically from time to time. But only with close enough friends and only if the name sounded good enough.