I mean, I know that the events of Daggerfall were pretty crazy, but even then, it seems odd how little High Rock is even discussed. In the 200 year timeskip to Skyrim, every province has been influenced or affected by the Great War or some calamity. High Rock, on the other hand, has seen very little action. The only things I can think of happening there is Peryite's plague and some rumblings in the Reach.

Why do the Thalmor seem to have no interest in High Rock? Why is High Rock relatively unharmed? Can we expect something to happen to it in the future?

The Thalmor have been murdering people, who they've deemed unclean in their eyes, on the island of Balfiera. They may have Direnni blood on their hands.

that's still not as big as a Civil War or an eruption

If they gain control of Ada-mantia, which is on Balfiera, then it will be.