It is somewhat random yes, but thats why I build offices one at a time, and then employ the person I want in that office. So I create the rooms in terms of walls, windows, desk, chair etc so it has all the requirements, but I dont apply the "Office" room type/overlay.

I then apply the "Office" room type to one office, and hire the desired staff member. Apply "Office" room type to the next one you want, and hired the desired staff. Repeat until all are assigned in the order you want.

Yeah, its a bit messy, fiddling around, but its all we have at this point.

An office is an office. Is it just for the look?
And you can get what officers you want in each office if you build and hire in order.

Yeah, but that is still annoying. I didnt knew this trick until @Engioc told me about it. Imagine if someone did not knew this before.