Like I'm looking into a bizarro mirror... who is this? Gifted Unlimited Rhymes Universal?

Re-themeing an 80B is something I've been planning out for a hot minute now.
ROM change, probably not. The 80b soundboard is basically a digitally programmed analog synthesizer. I don't know how to write ROM files, so I guess it's theoretically possible but I wouldn't know how. Maybe www.hobbyroms.com could point you in the right direction for that.

The route I'm planning on going is having an Arduino Uno receive the soundboard signals from the driver board and have the Arduino control the sparkfun/robertsonics wavTrigger. www.sparkfun.com

80b soundboard operation simplified: There are 5 input lines the board receives all at HIGH, when the signal goes LOW, it triggers a sound on the board. 5 signal combinations of high/low = 32 possible sounds (2x2x2x2x2) [e.g. signal one low + signal 2 low = sound 6, I don't know that this is the exact correlation but it is just a possible example]

If there was a way to use the original board and reprogram the ROMs, that would be fantastic as I love the analog sounds generated by the board. But at the same time, the capabilities of the wavTrigger are pretty impressive

What machine / theme are you thinking?

Seeing the code for the sound ROM, to me it looks... complex AF. Granted, I am not a programmer by any means; my knowledge is limited to a semester of BASIC back in high school and what I've taught myself so far about writing sketches for Arduino.
Though after seeing this, I would definitely say that reprogramming the ROM to play what you want is a possibility, just not one I can viably do myself.

For the Goonies re-theme, the guy used two mp3 triggers. He had to use two because the mp3 trigger/board/card is not polyphonic, meaning it could only play one sound at a time. So two were used so there could be simultaneous bg music as well as sound effects. The wavTrigger (which came out after the Goonies was completed), however, is polyphonic.

To activate the sounds on Goonies, a second switch had to be added to every actuator of every rollover/under/target for everything that caused a sound and was directly wired to the trigger input of the mp3 board. Quite tedious. Both the mp3Trigger and wavTrigger boards can be controlled via serial data from an external source such as an Arduino or other micro controller (Raspberry Pi for example).