1. I created a beta version of my TESTBED3 Mod and uploaded it. 2. Then I changed many things in many experiments but I have not uploaded this. 3. Now, I just want to roll back from my experiments. 4. Could I take the copy of my mod from workshop/content/33420 on my PC and overwrite it in Cossacks3/mods? Would this do the trick? UPDATE: I think I can answer my own question. It's not in workshop/content/33420. It's not duplicated there. That'll teach me to keep more recent backups. No matter, I can manually code it back.
It should totally be in your workshop content, actually as long as you are subscribed to your own mod.