Brygun - Thanks for this great project. I'm getting back into the game after a few years away, and playing around with this has been a lot of fun.
There are a couple problems I've noticed (from the BAC mod v026 download a couple days ago; didn't see either of them explicitly addressed since then):
The "Braced Bark Hull" recipe from the Transport menu calls for Tying Equipment ({Tying Equipment} (1)[ground] [remove] [noquality] '+tie ends of belly frame') but none of the tying equipment I've tried to use, including Birch Bark fibre cords/rope, root ropes, hide cords, and others, have worked to fulfill that step. I suspect {Tying Equipment} may not be working as you intend.
Second, the recipe for Birch backing in the bowying catgory calls for {Split trunk}. From what I read in the development thread, I think this may need to change to Quarter trunk?
Again, thanks for the great work.