You should be using mcjty.rftools not com.mcjty.rftools because you don't own mcjty.com.

Move done

Where does it say that you actually have to own .com in order to use package name com.? Just curious. I never heard of that.

From the Oracle website:

Companies use their reversed Internet domain name to begin their package names—for example,
com.example.mypackage for a package named mypackage created by a programmer at example.com.

Also, common best practices.

Well I don't own 'mcjty' domain either. So why can I use that then?
I don't think I will change this. I see practically every mod starting with 'com' in their package name and it is a major hassle to change this.

Well mcjty just isn't a valid domain name. As for the second thing, refractors all the packsges should be too hard if you use a good IDE, I know for a fact that in IDEA this can be done by dragging the package to a different location.