Nest locations can be seen on the interactive maps linked in the original post.

Game update 312.9 changed the spawns of Ember Wyverns which CG was reliant on, and so no volcanic dinos (incl. Magmasaurs) spawn in the area. This means there are no Magmasaurs in the area to spawn the nests at the moment.

Is it safe to assume that the Magmasaur spawns have not been temporarily relocated with this latest update?

They weren't relocated as the group container I used is no longer used in the game.

I have updated the mod a couple of hours ago, it should now use the new spawner.