Some observations that may be helpful for any future web searchers: I was primarily interested in getting the Saturn version of Nocturne in the Moonlight (AKA Symphony of the Night) running on the Switch, preferably in English. There are three notable hacks of it I tried: the PSX English translation, the Extended 1.5 untranslated version with graphical improvements, and the Ultimate 1.1 version that has the Extended one's improvements as well as the PSP English translation. The first two work, but the Ultimate one crashes no matter what I tried, so I went with the PSX English translation. For the most part, it runs well, although one notable graphical bug is in the first room with the mermen - whenever you go near the bottom of the screen, an eye-searing flashing yellow bar appears on the top of the screen. It's bad enough that in portable mode, it left some image retention on the screen for a few minutes. This is the only place in the game (in both the regular and inverted areas) that it's this severe, and it's easy to avoid after first opening the map there, so it isn't game-breaking. My TV didn't seem to have any image retention, thankfully. My next problem was that I greatly prefer DarkAkuma's ZebraEngine NSP creator via Cave Database Manager, but I don't have access to 1.5 and have to settle for 1.4.6 in which the select menu is invisible. I figured out that if I placed the Texture.tex file from Saturn2NSP in the atmosphere/contents/[fileid]/romfs folder, it fixed it! The buttons are labeled incorrectly when remapping them, but they still correspond to whatever button you press, so no biggie.
Anyway, hopefully this wall o' text will be useful for someone in the future - there's little to no documentation for any of this stuff online.