I'll try to summarize:
1) the adventure idea is excellent, full of nice ideas.
2) the opponents are nicely conceived and well built using the 3rd edition rules
3) the maps are small and hard to use, and the staircases connecting the various levels of the fortress don't match.
4) the 'petitioner' forgers lack dramatic flair and interest
5) the fortress seems too mundane, given the fantastic nature of the idea.
Recommended as a source of ideas: I'd keep the concept, the characters, and design my own fortress and petitioner resolution.
Regards,
Alix