220 m² for a semi-detached house? Enough space

So on the plan, half of a house with 7x11m is already sketched out. That would be 77m² of ground area taken up by the house. At least 3m of setback distances to the house are required towards the street and on one side each. Parking spaces are still missing, but maybe those are on the opposite street?!

I just quickly measured it on the computer, so no guarantee of accuracy: According to your plan, the garden would be about 11m wide and 8m long (from the outer edge of the house to the property boundary), so 88m² in size. That would be the main place for the terrace, flower or vegetable beds, and possibly children's toys. To this part, you add the two strips on the other two sides of the house, whereby one will more likely become the entrance area, the location for the air-to-water heat pump outdoor unit(?), and the garbage bin storage area.

I would still try to look at similar plots (with existing properties!) so that you also get a feel for it. My in-laws, for example, have been living for 30 years (long time as 3, now as 2) on a similarly sized plot with about this garden share (without the strip, since it’s a terraced middle house) and they absolutely miss nothing. For me, it would be too small.

What is the yellow? Existing building that is being demolished?
Do you have additional car parking spaces?
We have a builder here who has to provide 2! parking spaces on a mini plot (10 meters wide, end terrace house, 3-unit row), maybe you can find the thread with these keywords via search or someone here might remember the name.
By the way, also very interesting, his problem with the terraced house, that all have to be built separately with different GUs, which would also affect you. Or is it being built with a developer?

If everything else fits, I would buy it. There is no reason against it.
However, we don’t know your family. If you want to accommodate 6 people with their own rooms in the house, it could get tight and there are no possibilities for expansion.
We ourselves had a detached house on 25x 9.5. The front yard took 5 meters from the back part.
But many there with similar sizes then gave up lawn, made a larger terrace and otherwise only bushes.

Well then: you can’t make big leaps in the garden, but it is quite manageable for 2-3 people so that you can also take a vacation there.

Practically nothing can be recognized in this colorful drawing without a legend. Floor area ratio, plot ratio, roof pitch, heights – everything is missing. So we can only speculate (which is not enough): the red areas could represent the new building envelopes, the yellow ones those of the existing buildings – somehow it just looks colorful and not clear.

The only "basis for assessment" left is the plot size: 220 sqm (assuming a floor area ratio of 0.4 / plot ratio of 0.8) could ultimately result in 140 sqm of living space per semi-detached townhouse half. Provide some basics, otherwise it remains reading tea leaves.

You can practically see nothing in this colorful drawing without a legend. Basic and floor area ratio, roof pitch, heights - all are missing. So we can only guess (which is not enough): the red areas could represent the new building windows, the yellow ones the existing ones - somehow you only see colorful and not clear.

What remains as a "basis for assessment" is only the plot size: 220 sqm (times, assumed, a basic area ratio of 0.4 / floor area ratio of 0.8) could ultimately result in 140 sqm of living space per semi-detached townhouse half. Provide some basics, otherwise it remains reading coffee grounds.

A two-story semi-detached house with a 30-degree pitched roof is desired. The object should have a base area of 7 by 11 meters. Yellow is the existing building and will be demolished soon; a positive preliminary building permit is in place.

What is the yellow? Existing building to be demolished? Do you have additional parking spaces for cars? We have a client here who has to provide 2! parking spaces on a very small plot (10 meters wide, end-terrace house, row of 3), maybe you can find the thread with these keywords or someone here remembers the name. By the way, also very interesting, his problem with the terraced house, that all must be built separately with different GCs, which would also affect you. Or is it being built by a developer? If everything else fits, I would buy it. There is nothing against it. However, we don’t know your family. If you want to accommodate 6 people with their own rooms in the house, it could get tight and there are no options for expansion. We ourselves had a detached house on 25x9.5. The front garden took 5 meters from the back part. But many there with similar sizes then gave up lawn, made a bigger terrace and otherwise just bushes. Well then: you can’t make big jumps in the garden, but for 2-3 people quite manageable so you can also take a vacation

The exact old building will be demolished soon. There are enough parking spaces available in the public area. I would currently move in there with my partner. I am not bound to any developer, so probably to build cost-efficiently, the other partner and I will choose one and the same developer.

I am not tied to any developer, so to build cost-effectively, it is probably best to choose the same developer with the other partner,

And that will exactly be the problem if the other has a completely different building wish: basement/no basement, clinker/plaster, house style, roof pitch, etc.