The cupboard was customly made (no just kidding), it's pure coincidence that these boxes fit so perfectly.
If you hadn't said you were kidding, I would have believed you!
Like Bogro, I was surprised at how well those boxes fit into the shelving compartments.
Your Playmobil room is amazing. It would be nice to see some sets out of their boxes too, but I can appreciate that some collectors prefer to keep their sets sealed.
I hope you have your collection insured. It would be incredibly difficult (perhaps even impossible with regards the rollercoaster set) and prohibitively expensive to replace some of that stuff.