On the fifth session? What does that mean? "At the fifth session" is wrong.
Yes, that would work with "At the fifth stage" or "During the fifth stage."
There are discussions about a certain topic. They do this in weekly sessions.
Okay, but "on the fifth session" should probably be "at the fifth session." Don't you think? I'd say "during" the fifth session, but durante was not one of the words in the sentence.
I don't know. I am not a native English speaker, and the differences between on and at sometimes evade me.
Could it not be on the Thursday performance or session?
I think it would be "Na sessão da quinta..."