You were in Geneva, the passenger was speaking French, and the check in agents needed you to help understand what they were saying? But apparently the same passenger who was struggling to be clear at check in was confident enough to speak to you in the lounge and wangle an upgrade on board?

I still find it bizarre the check in agents referred to you to clarify the rules as well for this person who you had already confirmed had nothing to do with you.

The whole thing gets more odd the more you try and explain it tbh.