Thread:Zmario/@comment-35276917-20180605121948/@comment-416633-20180605131223

You can change the name of usertags by accessing the MediaWiki for it. It should appear under MediaWiki:User-identity-box-group-sysop. You can replace the last word with the user right you want to change (rollback, bureaucrat, etc).

As for your other question: I'm not familiar with adding new user rights so you might want to ask on the forums for help regarding that.