Thanks, this does seem to be the case! Whilst you can not check your traits on an existing character afaik, I was able to test this by removing the wings trait from the .slic and it did in fact affect my save file, so I would assume the passive traits are affected too, thanks for the heads up!
You're welcome, glad I remembered it correctly.
I'm surprised we can't check it in game in the status page, but that's what the character edit is for, I guess. It's a bit annoying to have to exit out of the game and relaunch it just to check. A quit to title screen option would be nice or a way to check and or edit our custom characters in game. But that's all QoL. I'm sure it will come someday.