There should be a written test when mentors apply for the certification where they are tested on job and dungeons/trials/raid mechanics.

Example: 1) What is the general opener for a 'insert job here' and what are the more niche openers and describe what kind of situations would you prefer the niche compared to general opener. 2) Describe the mechanics which you encounter in 'insert dungeon/trial/raid' here and explain how you would resolve such mechanics.

In addition to the written test, all would be mentors have to clear all current savage raids and extreme trials to prove that they are decent at the game (I'll exclude ultimates as that might narrow down the potential applicants too much)

As for trade mentors, it's a joke and should be completely removed.