Judging at tournament

My flgs has asked me to help facilitate a kill team tournament. The store has an employee who plays kill team, he asked me to help with the tournament because he feels rusty in the ruling department.

I have played KT around a year now and know the core rules pretty well aswell the ruling for like 10ish teams. My problem is that sometimes I get obscure ruling questions that I need to help to decipher.

When I was into Yu-Gi-Oh you had to take a cours on game ruling to be able to judge tournaments

Tldr: how much experience and rule knowledge does a person need to be judging a tournament?