Well, in theory you should be able to do a rename in-place, even GitHub encourages and supports simply renaming a fork. But there is a lot of config and such within the files, IntelliJ setup, pathing, etc, that need to be renamed manually. You'll have to find all the references before it'll work
Then if we do something new within Terasology and you want to copy it you'll have to catch every relevant rename all over again, each time. Initial rename is relatively easy compared to porting over maintenance changes and such over time.