Is it recommended to have a bathroom and toilet with few wall tiles?

just keep at it and see what you like best, finish with a whole tile so the edge looks good

end with a whole tile so that the edge looks good

I agree, I would orient myself by the tile height there. In our rental apartment, for example, we have about 120 cm of tiled backsplash (4 rows of 30x60 tiles), which does not seem to be that unusual. (Our developer now also has that as the standard for most areas) If you have narrower decorative tiles or a border or something similar somewhere, I would probably adjust accordingly and not say "but I want exactly xy cm of tiled backsplash."

I would initially leave out the side wall of the toilet.

Is a toilet paper holder going on the wall? Where does the toilet brush go, and where will the bin for feminine hygiene products be placed, if applicable? I would feel more comfortable with tiles on the wall there (it only takes one thing to go wrong), but ultimately it's your decision.

the specified sanitary fixtures, or door or window openings provide the templates in the room

I would not go over the top edge of the frame.

That means, if I let the tile of the washbasin protrude 30cm, then the wall-mounted faucet would be relatively centered on the protruding tile

In my opinion, that would look crooked, I would finish with a "non-perforated" tile.

where is the waste bin for feminine hygiene products possibly located?

For most of the planning gentlemen, that is probably an oops-forgotten question.

That would look wrong to me, I would finish with an "unperforated" tile.

In case of doubt, there will usually be a mirror above, so you probably have a quite good finish that way. But once again, this shows how difficult it is to answer that in isolation.

Thank you all.

That would look wrong to me, I would finish with an "unperforated" tile.

I didn't quite understand that. So finish the tile under the wall fixture?