Yes it does.
So, I looked at 5E. It looks like this is something with only on a few things. For example, any of the Premade races and classes, once dragged, I can't even unlock them. However, if I make a custom race or class, then I can unlock it, and any changes I make will also change the original entry.
Feats is a little different because, as you pointed out, it makes a copy. I will look at the code more closely tomorrow to see if I can find the difference.
That said, any changes you make right now will will change the main entry, but only for that campaign. It will not mess with the actual modules.
As far as i can think, I don't know what would need to be changed that wouldn't effect everyone. If you modify the Vulcan, than I think all Vulcans would have the same modification. I do know there are certain traits that could adjust scores. I have not looked into those yet to address it, because I need to read through it again, and play it more to find those side cases.
If there is something specific I should be looking at that would need to be adjusted on a PC by PC basis, let me know. If you want to take it to Discord, so we don't have to bog down the forums, that's fine too.