I posted this on Reddit and was encouraged to bring it up here, so figured I'd give it a go.
This is kindof a complicated question so I'll try to explain everything as concisely as possible.
The Halfling and Orc weapon familiarity feats are worded as "For you martial [ancestry] weapons ARE simple weapons and advanced [ancestry] weapons ARE martial weapons.
Every other ancestry weapon familiarity is worded as "For the purpose of determining your proficiency, martial [ancestry] weapons are simple weapons and advanced [ancestry] weapons are martial weapons.
There may be other situations where this could come into play, but the biggest instance of inconsistency that pops into my mind is Ruffian Racket Rogues. Per these rules, a Half Orc with feat could get backstab damage with Orc Knuckle daggers, because for him they are a simple weapon. However, a Goblin with feat could not get backstab damage with a Horsechopper, because it's only a simple weapon for proficiency purposes.
My question is has it been clarified if these wording differences were intentional, or if all the familiarities were supposed to work in one way or the other? This is also going to factor in more as they release more ancestries/ancestry weapons going forward.
Thanks to anybody who may be able to shed light on this, if there's something I'm missing.