The door thing is interesting. At least I think so! Maybe you would like to know why doors are hung the way they are? Traditionally in the UK doors are hung so they open with the leaf going into the room. This does two things. Firstly it makes the room a bit more private. So if you're doing something in the room and someone else comes in then they don't see immediately what you're up to, but you have a bit of notice that they are coming in before they see you. This means you can quickly hide anything that you don't want to be revealed to the other person. This is more of a thing if you have staff and then you want to maintain some level of privacy from them. Secondly it helps with draughts. Older houses are especially leaky and you can feel the movement of air. That air movement has a kind of internal wind chill factor. When you have the doors opening into the room then it slows down the flow of air, because it has to go around the door instead of straight in, so you can reduce that air movement a bit. In warmer countries, like Spain, where they want to keep doors open and out of the way so they can maximise air movement to cool the space down, then traditionally they have the doors opening against the wall. This way they can keep them held open more easily and have more air flow. In more modern or upgraded homes the draughts are not so much of an issue, and most of us don't have house staff that we want to keep things private from. So it can make sense to have the doors rehung. It's worth knowing the reasons behind the way they're hung, so you can be more selective. Perhaps in some rooms you would like to maintain that privacy, perhaps in a bathroom, and then you could hang the door in a way that works best. It's a lot easier to get furniture in and out when you hang the door to open against the wall. Hope that's interesting for you!!

So, has the approach to your property changed at some point? Because I would expect your entrance hall and front door to be at the front and not at the back? Could you turn it around again? If not, maybe move the front door to what is now the kitchen, making the kitchen part entry hall and part utility (dividing wall). Then you could perhaps create one large kitchen/diner/family space from the current utility, office and family room. The current dining room could be an office? Obviously all depending on whether all that would be possible re: load bearing walls and all that.

The circle idea is interesting and I understand why you gave the architect the go ahead to explore that concept- but you have to really want to live in a unique building to accept all the compromises. The compromises seem to be- the build cost will be significantly higher than building angular spaces, the three properties are significantly different in size which will inevitably lead to comparisons, you have the smallest unit as both siblings have an upper floor, extending later will be complicated, privacy may be an issue, visitors may get confused which entrance to use and your door may receive unexpected guests, the distance to both siblings doorways seems a long way from parking and the light levels will be different in each house because of the orientation of the windows. Separately if you have a 1 bedroom, 1 living room home then it’s difficult to create hidden spaces. Personally I think the courtyard gardens give you an element of that, the curved walls will be visually interesting. If you stick with this plan perhaps you could add floor level changes and internal screens to divide the spaces to given a less open plan feel

Consider turning the current upstairs master bedroom and Ensuite into two children bedrooms with a modest bathroom in the middle. This would mean you would have three upstairs bedrooms but personally I would convert the two downstairs bedrooms into a master suite where the head height is better than upstairs