Talk to Rockwell about the reason they wont let you edit tags.
I think when it came up it was something like if you edit the tags then should all the tags that reference that tag also edit? or just be errors that there is no tag? So, to save people and rockwell time they decided you can duplicate the tag, and change the name. But if you delete the old tag its on you for deleting it.
As for moving tags you can't but you can duplicate and then delete the tags you don't want anymore.
Or just move everything to an excel file and then delete all tags (in factory talk) and reload from excel after you fixed everything. The HMI screens will need the new tag paths or changes though.