Bathroom and fountain located in the basement can be turned into a single space (all issues in the interior design process can be solved)
by using a flower/tree box and placing it along the path of light and combining that with fountain of basement and greenness of plants in the path of the stairs ! Bring sense of nature into the house and enjoy it !
(For example, put a decorative natural pine to decorate it for Christmas, of course, any tree that you like and is compatible with the climate of there can also be a good choice)
If you like a dark basement because kept of your wines and want to have a bright bathroom, there is no need to worry, and for that, in the next steps, I have ideas for designing that you will be able to adjust the natural light and brightness to the desired level!
Place a sculpture, modern abstract or 19th century style in the space between the stairs of the first floor to add to the magnificent spatial geometry of your home by combining it.
Even a comfortable chair that you can sit on and see the balcony and the view behind it in front of your eyes!

To expand the basement space and increase its size, you can even increase the height of the ceiling a little by maintaining the same lovely stone structure and, of course, strengthening those walls ...
I think it is necessary to strengthen some load-bearing walls from the inside with the help of modern knowledge so that you can reduce their thickness and add more functional space to the building!
The height of each entrance staircase can be changed from 10 cm to 18 cm depending on the slope of the ground in front of the building.
In my opinion, it is better to change the place of the shelves in order to improve and strengthen the performance of load-bearing walls, as well as to improve the geometry of the plan ...
To understand better, pay attention to the submitted ideogram, due to lack of time and other reasons, I had to enter the description in English ...( There may be translation errors in some parts)