The use of a TRI for Line flying under supervision is only to be logged as instruction for training zero hour candidates who go straight to the line after using a level D sim, without the take off and landing requirement. Normal Line Training Captains do not have to have any EASA instructor requirements.
If you were in this situation both your TRI course and your AOC company would have briefed and trained you accordingly. If you don't know I would suspect just log instruction in the sim. It will be a safer bet when you go to become a TRE with your 50 hrs instruction.