Roof ventilation

[ab12]

Probably a daft question but is there a need to use ventilated fibre cement tiles in places on a pitched roof if when using a  breather membrane. I suspect not but thought about belt and braces option.

My current roof has old bitumen felt under fibre cement tiles, is ventilated at eaves and has a few ventilated fibre cement slates in places for airflow.

Thing is old roofer actually cut through the felt just under ventilated slates and this is allowing water ingress in places.

 

Also is there a need to leave an air gap between insulation and breather membrane when using an air and vapour open memnrane?