Bathroom planning 14m², new build, square, two windows

If it were mine, I would rather soundproof + reinforce the wall to the bedroom and then place the toilet and bidet on this wall.

One could also swap the washbasin and the shower. That way, the shower is not in front of the window. I would always place the washbasin closest to the door anyway, since you use it the most.

Agreement, visually okay, but too tight regarding WC/bidet!
30cm + bidet 40cm + distance 30cm + WC 40cm = 140cm.
10 or 20cm extra would then be the "distance" from the WC to the end of the half-height wall. How that looks visually, I can’t assess without a photo montage.
For that, the wall becomes really unnecessarily long. You have enough freedom of movement to the right of the WC (when sitting on it), how wide is the passage to the shower?
I would put the WC by the window, since you sit longer on the toilet and at the window you are more private.

Consider whether you appreciate the advantages of the bidet (we had one for a long time and found it practical for quickly washing feet or soaking/rinsing out swimwear, otherwise I can’t think of any advantage). A shower-toilet is much more comfortable for sitting and offers various more comfortable washing options; we were able to try it out in the bathroom showroom’s customer toilet and were convinced afterwards. Regarding the price: we never missed the blow-dryer function, the basic version is fine.

I would like draft No. 4 from the original designs best. You still have a second window, so you don’t have to go to the window above the tub that often. I wouldn’t like No. 2; I don’t want to sit on the toilet with my back to the door. I would also like the design from post 4. I also don’t think it’s too tight. You can just try it out. If necessary, extend the wall by another 10 cm.

Here very roughly in 3D: