It is always "nice" to read that my thread here is being used as a warning about deep foundations for other homeowners. However, that was not the intention. :p
Our neighbor, just before Christmas, shoved a basement floor slab into his hole. It now looks like we have a 60cm wide strip footing next to our foundation, which is about 40cm higher than the rest of the floor slab, since the basement of the other end house neighbor is deeper and the issue of underpinning was already settled.
On this said higher strip, his basement wall will later be built, so he will have a kind of podium running the entire length of his house in the basement.
Apparently, the municipal council discussed the issue in a non-public meeting, since the building obligation has actually long expired. However, a response from our mayor is still pending.