My terminology is not inconsistent merely because it doesn't apply to games I'm not talking about. In VF, you cannot block a 12f attack at -12 regardless of how you got there. Any move that is +12 on guard is a guard break. A move, like P, isn't a guard break because it is only +2 on block. There is no 2f attack which you can guarantee after a blocked P. Being +12 on block is as much of a "special property" for Akira's 2P+K+G as being -4 on block is a "special property" of a character's 6P.
Your definition of guard break still seems a little bit iffy. Guard breaks removes the guard and opens the opponent up for followups. A +12 on guard, even though I don't think there's any example for it, means that the opponent can still block. So the specific Akira attack removes the guard and puts the opponent in +12 hitstun.
Using game specific examples, to coin terms, seems rather counter productive.
NRS games are actually an oddball in terms of hit/blockstun. Because there are special states which puts you in hitstun, but still let's you retain the ability to block. I think the only other game that does this is the spin state of P4A.