Hello,
Upfront i want to say i didnt download those other two links mentioned in the information, so forgive me if that fixes whatever this is...

But when i tried your mod, it was giving me errors in the chatlog "missing tags for bp_entity ##:zy-unichest" where ## was a single or double digit number. not in any particular order, sometimes the numbers were close and sometimes not. I use another mod called "Unichest" so im guessing theres some conflict there between them since it mentioned it by name (im assuming this would be news unless you happened to also use that mod). these popped up when i copied about 4 Unichests and pasted them. Also i think i got it when i placed a blue print that had Unichests, but im not positive. But most definitely when i copy/pasted. I took a screenshot of the chatlog lines, but i dont see any picture options here in these forums. im on Factorio's discord if you want to see them (I'm Schliematt, lemme know if you want me to post them in a channel or direct message). i think it gave a line per chest i was copying.

It stopped happening when i unloaded your mod. I may try this mod later when things are worked out.

I wasnt sure where to place the two new items, again those two links in the description might have fixed this, but i didnt see them til after i unloaded the mod and didnt know what they were for til i clicked the links (also after unloading the mod).

When i tried to place either, there was a poof of smoke and they disappeared back into my inventory. the one (unloader?) i noticed what looked like the railroad gravel at either end, so i figured out to put it in place of rails and have rails going from either end. It finally stopped poofing. and i could put inserters from it to a chest. the other one just kept poofing, i could see i could rotate it, but it didnt let me place it on top of rails, or in place of them like the other item, with either rotation, or next to the rail. So I wasnt sure what to do with it. From the ghost it kinda looks like it would go over a train that stopped, but it didnt stop poofin back to inventory so i dunno.

Hello, thanks for the detailed report.

The missing tags for bp_entity ##:zy-unichest messages are very likely a compatibility issue between my blueprint handling and Unichest’s custom blueprint tags. I’ve added a fix in the newest version so Fast Rail Loader should no longer rewrite unrelated blueprint entities and should preserve tags from other mods like Unichest.

About placement: yes, the loader/unloader placement is a bit unintuitive. They need to be placed aligned with rails, and if the position/orientation is invalid the item gets returned with the smoke effect. This mod is mostly a personal patch for my own megafactory use, so documentation and compatibility are still rough.

Please try the latest version when you have time. I can’t promise full support for every mod interaction, but this specific Unichest blueprint issue should be improved now.