How to best connect the Katja-Sprint?

Hi, due to increased radon occurrences (not really much) in our region, one should lay a Katja sealing membrane on the base slab when building a new house. My problem is I would like to install the electrical installation, IT, etc. on the base slab by myself. The problem is, of course, if I lay the cables on the Katja membrane, I damage Katja by doweling, etc. Now I talked to my brother-in-law who had the same problem and he solved it as follows (see picture). What is unclear to me is how do I connect the Katja to the wall barrier membrane above the leveling layer? I made a small drawing and marked the spot in red. Maybe someone from the forum can help me with this? To connect the Katja in that area, the plaster at that spot would actually have to be interrupted... Or maybe it is enough to simply pull the Katja membrane a bit up behind the plaster (I haven’t found out yet if that is even possible). Or is it even sufficient (the sealing is only for radon, after all) to accept the small gap between Katja/plaster/masonry?