Fatal Fury does not only change the language to japanese if your system bios sets this as region code, also the special moves are quite different between the japanese and usa version (it's still the very same software, it just changes its behaviour depending on your system's region setting).
Example found here: https://rq87.flyingomelette.com/RQ/R/NG/FF/1.html
So, what if you'd prefer the japanese special move commands but can't read japanese text? Without romhacking you'd be out of luck. The good news is, I already have a working patch that lets you set the desired special move layout via Soft-Dips. The not so good news is that it feels wrong not to hack the animation sequences, where the moves gets explained - of course these would show the wrong command if the setting has been changed. I'm still working on it.
So, if you play this romhack on your MVS system you can alter the settings in the operator's menu, piece of cake. On the AES home console you don't have that menu (if not using unibios), so I was thinking about adding a detection for held-buttons on power-on.
E.g. something like
(A) held: short intro
(A) not held: long intro
(B) held: Japanese-style special moves
(B) not held: US-style special moves
I'm not asking how to do this, but if this is something you'd find useful.
