I managed to get this MAME XML cheat. Since the Japanese ROM is the only one containing the Japanese title screen tiles (the World and USA ROMs have corrupted Japanese title tiles, as shown in the previous image), this cheat allows the Japanese ROM—with its region byte changed to "World"—to boot up in Japanese mode (retaining the original Japanese intro, title screen, and "Insert Coin" screen). Then, upon entering the character selection screen, the ROM switches to "World" mode while keeping the English language. How can I permanently apply this behavior to the ROMs, or achieve something similar?
(The Japanese ROM can be completely clean, with no changes to the region byte, and the cheat will have the same effect.)
(The cheat can be used on any ROM from any region with the same effect, but only the Japanese version will display the title correctly.)
<cheat desc="Solo Logo Japones (Mantener textos en Ingles)">
<script state="run">
<!-- Si el juego esta en la intro/pantalla de titulo, pone la region en Japon (00) -->
<action condition="maincpu.pb@FF8009==00">maincpu.pb@FF82BF=00</action>
<!-- Si sale de la intro, devuelve la region a World (04) para mantener nombres y textos ingleses -->
<action condition="maincpu.pb@FF8009!=00">maincpu.pb@FF82BF=04</action>
</script>
</cheat>