Basement originally partially concrete, now possibly completely brick-built

In the case of a slope, I think it is not so bad not to connect to the rainwater drainage system, since the water is still directed sideways next to the house and from there no longer poses a threat to the house.

I have now spoken on this topic with an architect (the one planning the house) and an engineer (from my circle of acquaintances).

Our architect leaves it up to me whether to brick or to concrete.
Here are both variants between which I can choose (regarding a wall in contact with the earth/ towards the slope):

bricked
- 42cm hollow brick masonry
- sealing material RSB 55Z
- studded membrane
- no gravel layer
- drainage at the height of the floor slab for lateral water discharge, possibly with inspection shafts

concreted
- WU concrete (thickness unknown)
- thermal insulation layer (thickness unknown)
- no sealing material (because unnecessary due to WU concrete)
- no drainage (because unnecessary due to WU concrete)

As an advantage of the brick variant, the architect mentioned that it is easier due to thermal insulation reasons in combination with the creation of a support surface for the facing bricks.
Another advantage of a brick wall is that no transition joint to the definitely bricked remaining/above-ground part of the basement arises, but everything would be one piece.
He also mentioned as an advantage that the bricked basement leads to a better indoor climate.

I have read and heard the latter justification very often and have also seen it described as a "wives' tale" and then again as "probably true." A few colleagues reported to me that they themselves were able to actually notice a better climate in bricked basements by comparing with neighbors and their acquaintances. I do not want to judge this, but I give the "better indoor climate" a little credit.

The engineer from my acquaintances confirmed the two approaches of the architect.
He built his house himself and bricked it back then because he could do it on his own and had no options for concreting.
Due to groundwater, their house is permanently in water; back then they had to work with a drainage pump, and once when it failed overnight, the excavation pit was a complete pond the next morning.
He has had no problems with moisture in the basement until today (about 30 years ago).
He says if we build with drainage, it is no problem not to use WU concrete; the latter would certainly be more watertight, but definitely with certainty.

From the point of view of our well-known electrician (doing the electrical work himself), a bricked basement would be advantageous for the internal installations.

In summary (according to my interpretations), a bricked basement therefore has almost only advantages, except for the issue of watertightness.
The latter is the big unknown that no one wants to predict.

The statements of the above-mentioned persons contradict most statements here in the thread.
As it stands now, I would toss a coin with a slight tendency to trust the people I have met face to face more.
Otherwise, I am also considering seeking a consultation with a supposedly independent expert.

After yesterday's discussion with employees from the building materials trade as well as an acquaintance who is a young architect, I decided on a WU basement. From all sides, a WU basement was warmly recommended to me. One of the employees from the trade has already supplied other houses in the construction area (same slope, that is) and also already knows the mountain from another area, as he says, and especially recommended the WU basement.

The aforementioned acquaintance/young architect also advised me to consider a "fresh concrete bonding foil," which should also ensure the vapor impermeability of the WU concrete. Otherwise, it could already happen at moderate water pressure that a cardboard box directly next to the concrete wall could become soggy. I find information about this mostly from the manufacturers themselves; it is described that the foil is embedded from the inside with the concrete.

Has anyone had experience with this before?

I have now received the following proposal from the architect, I think it looks quite solid.

Architect-builder in personal union is, in my opinion, a favorable combination when he builds properties for his own rental, but an unfavorable one for the classic client-builder: from the client's perspective, the architect should be biased in favor of the client; the builder, on the other hand, has his own interest ("to be able to build cheaply in procurement") and it is enough for him if the place lasts beyond the warranty period (VOB shorter than the Building Code!). This corrupts his decision for building materials / construction methods: concreting requires a high proportion of experienced workers, while apprentices can help with masonry, and labor costs more than material. Just my 2 Cents ;-)

I have now received the following proposal from the architect, I think it looks quite solid.

my spontaneous first glance at the drawing says: half a centimeter more "air layer," and you stay neatly within the grid of the reference dimension inside and outside.