@CatBus: Of course I'd probably prefer getting the subs unchanged, but if your tweaks aren't anything major I guess it could be ok. Send me a pm!
@Doctor M: Thanks for the tip! I don't think we'll need to do it that way after all though.
It seems I had saved the character matrix file from when I captured the swedish subs from the PAL version of each film, so I tried using it again to capture more languages and it worked fine and I could easily correct some small errors and synch it using the timing of my synched swedish subs.
So now it seems the BDs will also include danish, finnish and norwegian subs.