Insulation for "ventilated roof tiles" – and the covering

Hello everyone; Hope I’m in the right place here :) We want to convert our attic and insulate it from the inside. It is a half-timbered house with a normal gable roof, one side at 45 degrees and the other at 55 degrees pitch. Currently, unknown roof tiles are installed, and a known roofer told me that I am not allowed to insulate underneath because they are internally ventilated tiles. I’m uploading a few photos. Maybe someone can tell me something about them. My question now is: Are the red and brown tiles equally internally ventilated tiles, or are they the same? It seemed that the dark brown ones are of a different type. It would be nice if someone could possibly explain to me the properties of internally ventilated tiles.... and the result when insulating.

If your acquaintance is an expert, why don’t you trust the statement?
What is anyone supposed to recognize in the forum based on 3 photos? Especially since all of them are from the outside?
Good luck!