12x9.6m 2 full floors, basement, attic, 4 children's rooms

That your mother is in a wheelchair does raise questions for me. What are the chances that she can spend the night at your place and be able to use the shower?
So far, for simplicity, I had assumed that the office between the bedroom and bathroom on the ground floor would just be demolished when a truly barrier-reduced/-free bathroom is needed. Do the toilet and washbasin at least fit a wheelchair user in the current plan?

I also think you can do without such a guest WC.

It "doesn't fit" above all: every detail can contribute to a house feeling cramped. And this WC overall simply looks like it was planned for a motorhome and not for a house. And a tiny little office needs extremely increased air exchange if you are supposed to be able to concentrate in it. Cubic capacity cannot be replaced by anything.

...
I designed the two office chambers according to our requirements. I simply need a small room where I can work and make phone calls undisturbed. My wife wants her own room that she can lock so she can sometimes leave things "open" without the children getting into them.

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You know, I assume that everyone would like to have a room they can lock behind themselves.
But the fact is that every square meter costs money and should be accommodated in qualitatively livable rooms that can be used for several activities.
And so you make arrangements and combine the needs of the man and the needs of the woman and have a nice room where everyone can develop themselves individually. And if necessary, even together, if the children don't mind.

But even the discussion about the guest toilet shows that you are still approaching the planning with quite a bit of tunnel vision. You also build your mental barriers into the house.
And then later you wonder why nothing can be properly fixed.

I find the two chambers, intended to find peace, contradictory again to the living area.
You plan the living room as a passage room. That’s not nice. It has no advantages. The idea might be nice that you are right in the living room, but practically with children it's something else.
Nobody wants to be watched by the postman while lounging on the sofa. And if in the evening a teenager wants to get something to drink from the kitchen with a girlfriend, as a sofa sitter/parent you don't want to be interrupted from the exciting crime show.
Not to mention the neck strain. That is not a proper TV setup but a makeshift solution because it wasn’t thought through.

Well, I don’t want to talk you out of your opinion, but awaken the spirit for everyday practical use, even 10 years later.

And so one compromises and combines the needs of the man and the needs of the woman and has a nice space where each can develop individually. And also, if necessary, sometimes together,

In my opinion, a home office should have the side effect that the spouses have a bit more time together during the day. To be in the same house with my wife but only in contact via webcam, just because everyone is stuck in a single cell, would feel strange to me.

True, a 60 cm door is certainly no luxury but we have been living here for 7 years and everyone, really everyone has managed to get through the over 3 m long corridor (65 cm wide) into the bathroom and back... and the guest toilet is for guests who want to quickly relieve themselves. Especially when drunk, this way you can better keep the direction

I'm out for now...

So, I was a civilian service worker for assisted living, and my parents remodeled their bathroom to be disability-friendly a few years ago. Therefore, I am quite familiar with what is possible in a bathroom (with a wheelchair) from my own experience, especially since the houses for assisted living were all retrofitted to be disability-friendly (not really remodeled) at that time. The bathroom as it is currently planned also works with a wheelchair, because 1. there is enough space to the right and left of the toilet, 2. the sink can be made wheelchair-accessible if needed, and 3. the shower is wide (I know, it should actually be 1.5 m) and long enough to shower with a wheelchair. There is also room in the shower for a seat.
Don’t get me wrong, it’s not a large bathroom, but it works. If you leave out the guest toilet, there is even more space!
Whether you need the guest toilet or end up leaving it out doesn’t have to be decided today, but in the past, I have had no problem using the bathroom "for everyone" either at our place or at others’. You don’t exactly rarely encounter that in the city. As we already wrote before, we have our own caravan, so I am quite familiar with a really cramped bathroom/toilet. I’m still really looking forward to every camping vacation (please don’t start a discussion now whether that’s comparable). Currently, as I said, we have 3.1 sqm for bathtub, toilet, and sink. One could also say the bathroom is not exactly a prestige object for us.
The air exchange in the office is ensured by the ventilation system. In addition, there is a 2 m wide window, and if that is not enough, you leave the door open. Until the kids come back from daycare/school, the latter is no problem... and yes, due to working from home, of course I see my family more than without. Why I am sometimes still not allowed to close the door (especially when making phone calls) is beyond me.
There is a door between the stairwell and the living room. You only see the mail carrier when it’s open.
From some comments one might suspect that fundamental laws are being proclaimed. Other opinions on the floor plan are always welcome, but you can also agree to disagree --> live and let live!