For whatever reason, even if I trigger the compatibility check built-in to this mod, the trains from this mod https://mods.factorio.com/mod/se-space-trains never get fueled up? I don't see a fuel category for them either. Got any clue as to why?

Hi there! Thanks for letting me know about this!

All trains should be compatible, so this is probably a bug. I'll take a look and see if I can figure out what's going wrong!

Also, those trains have a used fuel output that can then be reused, would it be feasible and relatively UPS-efficient to have a method of centralizing returned fuel from stuff like this? For context, I'm playing Space Exploration and as those trains use that fuel, I'd be refurbishing the fuel cells and there's no way in this mod to(as far as I'm aware) prioritize specific ammo loader worker chests over others, or to centralize the scattered fuel.

Hm... interesting idea! Actually, I think that would be an excellent feature to add to the mod and should be feasible without too much extra UPS overhead.

I'm looking into the bug you mentioned now, so while I'm at it I'll poke around a bit and see if I can't implement those features in some form. Let me know if you have any other concerns or suggestions!

EDIT:
Btw, would it be possible for you to link me your save file? It would help me identify the bug a lot quicker. Thanks if you can!

Here it is! Be warned, there's a LOT of mods lmao - btw the Texuga TA Miners is a personal edit, but it's literally just some miners so you can ignore it.

https://drive.google.com/file/d/10_pa4XQS0A5PTWt_bEfbLBJX0u0_144_/view?usp=sharing

I just uploaded 1.1.14 which should fix the bug at least. I wasn't able to implement anything regarding the burnt fuel, but I'm going to keep working on it! I'll let you know once I've got a version up that has that feature.

Let me know if you have any more issues!

Any news on a potential used fuel return? Would be nice for nuclear reactors too!