Regarding improvements, I think you could give some special abilities to unique buildings from Athel Loren, for example, the High Elves ability Hammer of Vaul to break walls. Since high elves lack artillery, this could be particularly useful and would give Vaul's Anvil (Torgovann) meaning, and would spread around the abilities in the different regions of Athel Loren instead of being focused on the Oak of Ages. This could also allow you to assault settlements on the first turn even if you lack a siege attacker. Similar abilities could be done for the other regions. In fact, it could remove the focus of the abilities on the Oak of Ages and balance the wood elves factions. Currently, the only AI wood elf faction that matters is Talsyn because they own the the Oak, so fighting them is annoying as they spawn units on top of your ranged units. But if you fight the others factions, it's underwhelming as expected. This is just my take on it. Feel free to tell me otherwise if you think this isn't right.