Hello, just did my first playthroughs with your civs, and I really enjoyed them. My feedback:
1. Perhaps rename Gondor's leader to Elessar? Once Aragorn becomes the king of Gondor, he takes that name.
2. I know that you have already finished it, but I would suggest that Isengard be altered to fit a science/army production strategy. At least one of these middle earth civs should be geared for a science win, and Isengard makes by far the most sense (Saruman invented GUNPOWDER!). Saruman's greatest strength was that he could rapidly produce an army AND outfit them with rapidly produced steel weapons and armor in an era when humans had blacksmiths painstakingly work on each item.
Some sample ideas for Isengard (in no particular order or combination)
-gain science equal to a percentage of your production
-a unique workshop that also provides science and/or % on science
-a unique forge that increases the land unit production % and provides science
-manufacturies provide science as well
-conquering a city provides a large science bonus, capitals provide a free tech
-not to do with science, but I feel like worg riders shouldn't be about raw power but maybe start with the scout's terrain ability, combat bonus in rough terrain, and/or a flanking bonus, seeing as they serve more as shock troops than as powerful cavalry (hard to see wolves standing up against a cavalry charge) . Maybe even a 10% demoralize effect for their fearsome howling. The worg riders in the animated Hobbit movie gave me nightmares a child.