As both maps creators are still active, I would say mail directly to them - I for myself wouldn't like to see someone fiddle around with my maps/mods while I'm still actively working on them, 'cause at best both of us do the some work twice than.
It would be somethings totally different if I had stepped back from working on them officially, in THAT case everyone working on them would be very welcome.
Other possibility is to declare those fixes your own mods of those maps, and have them uploaded somewhere*, but don't forget to give credit where credit is due.. (*send maps/mods etc to
info@illwinter.com)
A.