I see, I have no idea if that is normal or not. It also seems odd to me that the two files use different slashes.
To refresh the launcher database, with the game and launcher unloaded:
- delete the file Documents/Paradox Interactive/Stellaris/mods_registry.json (if present)
- delete the file Documents/Paradox Interactive/Stellaris/launcher-v2.sqlite
Then run the game from the PLAY button in Galaxy.
If that doesn't help I wonder if I can ask you to check with the mod experts over in the User Mods forum here? They will certainly know more about getting manually installed mods working than me!