Are internal gutters problematic?

I just thought of something else, we also have 4 outside water taps that are supplied from the inside, and I am wondering how the water gets there.

For example, from inside under the screed. Or planned directly. Due to the statics, no pipes are planned in the exterior walls, of course there are penetrations. They do not affect the statics. But... my goodness: everything is possible. You just don’t have to do everything. Some things prohibit themselves. Whether this belongs to them? No idea. At least the roofer has concerns, and the question from TE is definitely justified - even if for some here it worked well for 3 or 5 years. The flat roofs from the 60s also remained watertight in the first years... some still do.