This seems pretty Low, with 15 Gold for 100min its better to Just sell the Wood instead of building additional markets.
Imo even 5 gold per minute could be ok, six markets would be the equivalant of one relic
Free ballistics and free archer line upgrades, either of which are top, and together will be an absolute disaster.
For either of these two to become a civ bonus, it means that the civ should no longer receive any other bonus than the team bonuses, and even then there is still possible to break the balance. I don’t think the dev would take such a risk.
Only the crossbowman upgrade is free, well it is safer but still a strong bonus. Maybe it allows to give the civ an economic bonus, but that’s it.
What’s so great about the Nubians in middle age? Just holding off one small muslim invasion and being three little tiny christian kingdoms (Nobatia-Makuria-Alodia). Their archers are already covered with Ethiopian bonus.
What niche do they really fill in game that is not covered?
Nubia completely annihilated the Arabs which was a pretty rare achievement during the Arab expansion. Also they had the best archers in the world in that time. They also dominated African trade until the 12th century. Is Battle Of Tours also minor? It had only a few more Arabian soldiers than the First Battle Of Dongola.
What’s tiny? It like the average European kingdom size. The 3 together was pretty big.
Europe has 4 cav civs next to each other (Burgundians, Spanish, Franks, Teutons) Nubia and Ethiopia don’t have a common origin.
Because they are different people with different culture. Nubians had better defenses, trade, cavalry, infantry (European-like weapons like Halberd and chainmail armor) and more stable religion. Nubia had nothing to do with Ethiopia in the Middle Ages.