One more known example should be Megadrive checksums. If you modify the ROM (smd/gen format, not bin) in any way you trigger the dreaded red screen of death at game start-up.
That's because the ROM has a checksum stored somewhere, and each time you fire up the game it calculates that checksum again with the current ROM data and compares it with the stored checksum.
I suspect very much this is some sort of anti-piracy measure (think about it, the BIOS has stuff -besides language- Sega wouldn't want tampered with at any cost...), obviously more evolved than Megadrive / Game Boy checksums.
If you had an emulator with a debugger and some familiarity with whatever assembly language DC uses, and maybe any Dreamcast documentation mentioning the BIOS and really anything no matter how insignificant its CRC check, you could undertake this task.
Though... it's by no means a small one.
You'd be basically doing much of the same work people hacking consoles do.
For perspective, most PS1 game modders in cases when the game uses the (ugly as a sin) BIOS font (examples: Castlevania SOTN, Clock Tower, ...) find it actually easier to reprogram the whole text displaying routine rather than modding the BIOS with a better font.
Maybe... you could look into doing a homebrew mock-up of the BIOS in the target language?