Wonderful. I appreciate that stef77 nudged me in the generic direction - the PR I opened now should support all modded fluids, assuming that they have a corresponding barrel recipe.
Something to note - I'm assuming that a lot of folks will probably want to use this mod with Barrel Fluid Icons (it just attempts to add barreling recipes for all fluids, modded or vanilla), but there is some issue that I've uncovered that I think has nothing to do with this mod (or the work that I did in that PR), but it's something to be aware of: https://mods.factorio.com/mod/BarrelFluidIcons/discussion/68a241749e5c054031411bbf
I'm hoping that it's easy to resolve, but if it's on the original mod to fix, then might be worth adding a disclaimer to the mod description or something to describe what to do.