Hi! I have another idea for the High Elves. It will be harder to play, but more interesting. You can take the mechanics of the electors, but in a limited format (without intra-imperial intrigues, without imperial authority and without a large volume of text). The essence is as follows:
1) At the beginning, we restrict or even prohibit the hiring of units that relate to a specific principality of Ulthuan (sisters of Avelorn, dragons, sword masters of Hoet, white lions of Kreis, and so on)
2) By capturing any principality of Ulthuan, we can appoint a ruler there (such as an elector), the elector receives an ability thanks to which the restriction on hiring units of this principality is completely removed
3) Additionally, I would impose fines on the price of keeping foreign troops for the elector (for example, the increased price of keeping the sisters of Avelorn in the army of the ruler of Caledor), but I would give bonuses with characteristics for native troops (for example, increased characteristics for the masters of the sword of hoet in the army of the ruler of Saferi)
4) For factions, there should always be no restriction on hiring their native units (there are no restrictions for the Avelorn faction on hiring Avelorn sisters and forest spirits, and so on)
5) Lords who are not electors should receive fines for the maintenance of special units