Stupid question, but just to be sure I wanted to ask here again: Are the pipes laid correctly? We are unsure about the distance between cold and hot water and insulation in the shower. But it's surely correct, right?
if the distance from center of pipe to center of pipe is 15 cm, everything is laid correctly. It looks good at first glance.
Regarding "Dämmung", what do you mean by that? Yes, the pipes are also insulated. Or do you mean the sealing of the wall? I would still be missing that before proceeding with tiles or wall cladding panels.