Firstly, I have to congratulate you, is indeed a exquisite model, which of course cost a great amount of effort and time, thank you for sharing this with the community.
Secondly, sadly, and I don't think this is happening only with your model, but is the first one I tried, after I imported the model, saved the map and closed it, when I try to open again it appears a Warning (the Warning that almost all of the time represents a corrupted or otherwise messed with archive), I don't know if it is a bug or somekind of problem that is only happening to me, but either way, I thought that it was of good will to share this problem that could've cost a map with a whole lot of triggers, thankfully I'd a backup, so, no worries, and if this is a post better placed in "World Editor Help Zone" I'll understand as well.
Again, great model, congratz and keep going!
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"Do what thou wilt shall be the whole of the Law"