I'm planning to run a campaign soon set in Isger, but I recently learned that there are no Pathfinder Lodges in Cheliax, mainly because Pathfinders arn't welcomed in Cheliax. Is that correct, and if it is, is it fare to assume there are none in Isger as well, since Isger is a vassal state of Cheliax?
Canonical Pathfinder Lodges are listed here, so it would appear there is no Lodge in Isger. (Note that the one listed in Cheliax is now closed.)
For the purposes of your campaign, you could rule either way: either conclude that there are no Lodges in Isger or rule that, since Cheliax views it as a glorified trade route, they don't pay that much attention there so a Lodge could be opened or maintained undercover. The caveat, of course, is that official material could later come out which contradicts your home canon.