Lovely work! You've done a grand job with that.
Glad to see you persisted with a Mini Art kit. I have bought a couple. The house was so badly engineered, I ended up binning it, just keeping things like the windows for the scratch build parts box. The fort languishes part made and unloved.
It would have cost them little effort and no real loss in modularity to have included tabs or keys to allow for better adhesion and plumb lines on walls.