I have to start this by saying I love my DD ( nearly 6) so much. She is our only & was a long time coming. She is our world.
When she was a baby, she was just the best sleeper. Seriously we were shocked by her amazing sleeping skills. Through the night at around 2.5 weeks without us doing anything in particular. Shockingly good.
At 2y or so we took her out of her cotbed rather suddenly as she managed to flip herself out - that same night DH took the side off the cotbed so we never had a chance to properly transition.
We live in a townhouse with 3 floors. At this time her nursery was in a small bedroom at the top of the house next to ours.
When it was time for her to get a “big girl bed” over a year ago (she was 4 at that time) we moved her into one of the 2 larger guest rooms on the middle floor, because she had outgrown the small room upstairs. It is lovely, and all of her toys fit in there, and it’s decorated with her input and interests in mind. We transitioned her into it properly. She was excited about it for a short period of time.... and then It did not go well.
For the last year or more we have dealt with her waking up, either screaming in an absolute panic scaring the bejeezus out of both of us, or coming up crying, or just appearing silently in our bed somewhere between 10pm-2am most nights and kicking and forcing us off the sides somehow.
She seems to be very upset she isn’t on the same floor as we are. She seems to be scared to be alone generally, but will sleep ok if she knows someone is on the same floor as her (in the guest room) or is in her room with her all night. She is currently asleep on the sofa downstairs and I will have to carry her up her when I go up in a minute- we have resorted to this as she just refuses to be put down in her own bed and it takes 1-1.5h to get her to sleep in her own bed sometimes so we just acquiesce to get her to bed on time and have any part of an evening to ourselves. I will probably spend 15-30 mins with her on the floor in her room while she goes to sleep after being moved.
What tends to happen though multiple times per week is one of us will go sleep in her bed and the other will sleep with her in our bed- generally for ease as both of us work and she has school and we are concerned about her lack of sleep.
We know this will not go on forever. And that we will miss her wanting to cuddle when it’s gone. However it’s very hard to deal with as we are just exhausted constantly dealing with it for the last 18 months or so. We have had couples city breaks away in lovely foreign cities where we basically just sleep. I would like to do that more locally ! 
Is it unreasonable to think that an otherwise happy 6yo should be sleeping through? I have become quite frustrated and resentful that we cannot help her to sleep well and it’s just impacting us a lot.
Am I crazy to think that DH and I should be able to have our own space, part of an evening & enjoy our marital bed (b/c really that’s been seriously hijacked) without fear of a tiny screaming intruder?
Any tips or thoughts on how to deal with the interrupted sleep properly in her own bed greatly, greatly appreciated.