Being a ~250 year old house when there is a breeze you can really feel it in the eaves. So it’s coming in somewhere.
The problems tend to arise when modern construction methods meet with the old.
Drafty old houses don't need to worry about ventilation as much, and the materials are breathable and porous.
Modern materials are much less so, and will prevent the older stuff from breathing / drying out.
Moisture can wick / pool, and you could end up with blown plaster, mortar turning to sand, rot and all sorts of other fun stuff.
I’m massively confused about why the mineral wool is against the sarkin.
Someone had the idea that it was drafty and cold, and decided the way to fix that was chuck rockwool up against it.
My mother, bless her cotton socks, was persuaded that the way to insulate the loft in he Georgian house was with polyurethane spray foam. It is not removable, has cause a damp problem that didn't previously exist, and has made it uninsurable and potentially unsellable.