This might be the place to ask. I have here a Sega karaoke machine, a very, very big machine (about the size/complexity/weight of an old school AVR, coincidentally it was made by Denon) that has multiple boards inside... one of which is a Roland board!

From what I can tell, it is an SC-88 derivative. Obviously a different board with different I/O, but the circuit layout and chip markings are a match. Large Fujitsu QFP160 in the corner marked Roland R00677245 RHR-2342, connected to four banks of 2MB D23C16000 mask roms, a DIP20 HN62444P, 2x 256k SRAM, 2x 64k DRAM (I think), and opposite side are two smaller QFPs one of which is a Roland marked NEC chip (R00349690 D65622GF) and the other being a Hitachi H8/510. That's the SC-88 chipset right there, or at least as far as I know. The machine also sounds similar to a Sound Canvas if my memory serves right.

The ROM data starts with the string "Roland XP-GS Ver.1.00".

My question is, is there any way to check what is in the ROMs? Perhaps some alternate patch set? Is there any sort of sound canvas emulator, that I can just pop the ROMs into to test what they do / how they sound? I just inspected the ROMs and apparently the dump I made back in 2013 is not correct (one is corrupted, and all of them were dumped as 1MB only), so I wonder if I should bother dumping it again.

You might as well dump it, so others can hump it. Then, they can lump it together with the latest experimental SC emulator and see what noise comes out.