Steve,
I assembled mine last week and found all the same things you did regarding "square" edges, narrow slots, and even a popsicle stick sanding tool! I wasn't able to find any of the acrylic cement you recommended earlier (in this small and remote community anything beyond carpenter's white glue is difficult to find) however cheap 5 minute epoxy worked very well. The thing may have to be modified to work on a Gotha however it's easily large enough to handle two seaters in 1:32 Scale which my AeroClub version wouldn't hold, and is why I invested in this one.
Thanks for posting this, I wish it had come a week earlier if only to validate my own thoughts on it. This should help others deal with any issues on the product.
Cheers,
Lance