Flawfinder,
WELCOME TO THE AWS WELDING FORUM!!
To COMPLETELY answer your question we will need even more than just to know which code you are inquiring about.
For instance, if his qualification was with 7018 but he is running wire then he is not qualified. You probably know that, but, bottom line is that more info in needed in order to answer your question with any degree of accuracy.
Applicable code, welder cert, welding process in use, WPS specs work is being done to, etc.
Have a Great Day, Brent