Unfortunately steam workshop does not clear outdated files, they just override what's in the folders if same name. So if you have like, event_file1 and a mod creator moved everything to event_file2, you'll still have event_file1 on your computer possibly conflicting with everything.
Literally no fix unless you unsub (deletes the entire mod folder) and resub (re-downloading everything intended to be in the folder).
Shouldn't be needed very often but as mods get more complex sometimes files become useless or change names for consistency.

For example, I currently don't use a scripted_triggers file. But I did. So you might have it on your computer. Probably fine and harmless, but not needed and surely would be found in your game debug/error logs.