ok, ACA Sonic Wings 3 mystery solved, thx to ohfivepro: Sonic Wings 3 has a bunch of exclusive, route/final stage-specific endings that are not present (or at least not accessible in the same way) in non-JP versions, and are not chronicled anywhere on the JP or EN internet, as far as I'm aware, hence why even JP folk thought they were new
...and, even then, my source was someone who'd been clued in by an erroneous, now-edited wiki article, and if I'd read the QRTs I'd have spotted that immediately, so that's my fuckup for today
every mistake has a silver lining: the JP-exclusive endings are being documented on TCRF https://tcrf.net/Aero_Fighters_3_(Arcade)#Regional_Differences