Is there a way to convert .npc files into .dat (or a way to edit already-created NPCs)?
No, you can't edit NPCs which already created in game. Yes, you can convert .npc to .dat file.
1. Open .npc file in text editor( I'm using VS code for it)
2. Search in text for
"body"
3. Delete all text before brace
4. Search in text for
"scale"
5. Delete all text after 2 braces
6. Save as file and change format to .dat
If you still have questions, let me know, and I'll describe the guide in more detail.
For the future, I'd like to ask everyone sharing their characters to save them not as NPCs but as a save from the character editor. The saves are the same for both NPCs and the main character, so please share your .dat files.
Shortcut for the game save folder, just copy and paste into the address bar in explorer
C:\Users\%username%\AppData\LocalLow\RalivDev\Archipelagates