Currently its not displayed anywhere since it rarely changes. Everyone, allies and enemies, have a base of 3 mana per second tho.
That's good to know! Can I suggest to put these infos in the finished/polished game? :D These things are great to know. It's not a must, but I always find weird to look these things up online for various strategic games, even AAA ones. Sometimes they don't show some data and I don't quite get why there is not a menu that shows them, somewhere. You can play without them, for sure, but why keeping them hidden? o.o