If you are trained with a bow, are you also trained with the composite version of that bow? I cannot find any rule text to either confirm or deny this.
I just watched one of the recent streams where the question was asked “Do magic weapons automatically bypass certain damage resistances depending on their plus like they did in PF1e, because it doesn’t say either way in the rulebook for 2e”
And the answer was no, they do not. They said if there’s a rule from 1e that is not included in the playtest rulebook, it was excluded because that rule is not in 2e and it isn’t feasible to include a “This Isn’t a Rule Anymore” list. So it’s best to assume that if the book doesn’t come out and say it, then it isn’t the case anymore
So, yeah, applying that same situation to the bow/composite bow proficiency issue I’d say no, you don’t get proficiency with composite versions just by getting proficiency with the regular version. Unless: A) We missed something, and it does say it somewhere in the playtest rulebook OR B) They made a mistake and intended to include it