Why didn't Areelu move to another country?
- Bad writing. In the original path, Areelu always was a devoted Deskari worshiper.
That is true, in the original path Areelu was devoted to Deskari. Who wasn't a brute or a red herring. Even Owlfinder's idea that Baphomet is the saboteur of the duo isn't the case in the path, because Deskari is behind everything then. Which means the story is completely changed and the answer to that question must change with it:
I think it's that Areelu had always been studying the abyss. And there's no better place to study the Abyss than Sarkoris, since it's entire planar existence shifted towards the Abyss after Aroden's death. The game doesn't outright say that. But I think it makes sense if you consider that Areelu managed to create the worldwound relatively quickly, and that her kid does summon a Balor in a flashback.
Areelu correctly thought she could get away with her studies indefinitely. Her mistakes were trusting another mage with her hut's location and letting her kid out of the supervision at all. So the arrogance is there.
Also his soul was directly judged by Pharasma and sent straight to the Abyss, so he was at least CHAOTIC EVIL and probably into DEVOURing soul.
It's important to note that the kid could have had the personality of a chaotic neutral or even a chaotic good, but just casting summon monster made them metaphysically aligned to being tossed into the abyss. We don't know enough about them (they are left vague on purpose for obvious reasons) to know the exact reason for Pharasma's judgement. But yes, we don't need to presume their innocence. We can only marvel at the stupidity of the last great druidic culture persecuting mages into it's own destruction. Survival of the fittest, I guess.