I had too much time in my hands, so I made a flashcards for learning civilization bonuses:
https://www.cram.com/flashcards/age-of-empires-ii-de-civilization-bonuses-11405182
I used bonuses listed on the AoE Wiki, so some bonuses might have different numbers than they have in the game (such as Malay).
Heads up though, I initially copied the bonuses from outdated civilization page (Link) which still shows things like Slav getting supplies and missing Khmer farming update. I tried to double check and correct the wrong ones, but I’m not sure did I manage to catch all of the wrong bonuses.
I also decided not to use leaked patch notes, because they are not in the game yet, but I might update the cards after the next update rolls out. Also, if you have any ideas or feedback, then please tell me
Cheers