The challenge you have here, is that if you add the tribunal of Scandinavia. you need to design its Hermetic history as well. You are absolutely correct that Scandinavia is not pagan wilderness in 1220. Iceland is Christian by parliamentary decree about AD 1000, Norway from soon after St Olav's defeat at Stiklestad 29 July 1030, and Sweden in the same century.
However, the fact that the Church lives peacefully in settled areas, does not mean that Hermetic covenants would not be under constant threat from magical and/or faerie beings from the wilderness, and there is a lot of wilderness. Not pagan, but virtually uninhabitable. There might well be threats that have kept the Order out, not necessarily human (OoH).
Comparing it to Britain, it seems that Hermetic colonisation depends entirely on a single magus with a great vision and determination to match. Such pioneers arise more or less at random, and not necessarily immediately when the land is ripe for the taking. Maybe that exceptional magus simply did not emerge until after 1220 in Scandinavia.
Thus, leaving Scandinavia out of the OoH seems perfectly plausible and consistent. Including would also make sense, but the map exercise does not suffice. One also has to decide when the tribunal was formed, how, and by whom, and one has to map out the magical landscape as well. As long as it is wilderness, to be explored in game, it is much easier for SG and the troupe to design it along the way. If it is settled, there has to be a lore which needs to be available IC and OOC.