Anyone doing DOA settings for finding stuff should always set to CH imo. 90% of your matches is CH anyway, and the only time you'll see NH land is if they crouch, let go of guard, if you throw while they are guarding, or when they whiff a move and you launch/throw. Otherwise there is usually no real point to have settings set to NH considering your real damage scaling is usually always "something from CH".
Reused assets is a rather common thing to be quite honest, so Tekken doing that is no surprise to me lol. Majority of fighting games reuse assets so it is what it is personally.