Currently since many Advanced Rocketry multiblocks have been disabled the airtight seal enchantment is rather difficult to obtain (only source I could think of is loot). It would be helpful to add a recipe for the enchanted book in the enderio enchanter if possible.

Not in the current latest release of Exa's fixes, but an unreleased release has a recipe, Probably will be added in some form, maybe in 1.3 even.

A recipe is added by this commit to 1.3-PR.
Might be a bit too expensive, though, but that can be tweaked in the future.