I ended up taking a look at some of the older runtimes, but I couldn't even get the game to compile with them anymore. Claims a "permissions" error which per a search of the internet has more to do with licensing than anything else. My guess is that they're basically blocked in the newer IDE versions for incompatibility or blocked altogether to prevent piracy of olds version.
And yeah, CC has a weird legacy being "the game you use to get Deltarune to run on Linux." I don't mind; I hope folks try CC and maybe even enjoy it, though.
Thanks for all the info, and good luck getting more stuff running on your machine! Drop a line if you get any of my games going on it!