Switching Fengheld and Irencillia

Anyone has any idea why Fengheld and Irencillia, in the official Rhine tribunal, are where they are? I'm considering switching them, as this seems MOST natural. The official location of Fengheld, the Harz mountains, is THE locale for faerie plots in the tribunal. And the official location of Irencillia is near the old druid-loving Diana-cult of old-Merinitia, a place that has a lot of Diedne vibe and I can totally see the conquering Schism-War veterans that supposedly established Fengheld setting up shop there; and I totally don't see why House Merinitia will want to stay in this magical forest, instead of moving its base of operations into a more faerie-friendly locale, like the Harz mountains.