Started with a bit of modding today. Custom fortress defense mod, with allies, enemies, thieves and cave-civs. I made 15 each, in 5 different difficulty settings. All use vanilla DF creatures as basis, so that players don't have to learn about made-up stuff by me. ^^
Love the idea. I was thinking about doing something similar but haven't the time (Army training begins shortly for me). Have you considered condensing them into fewer civs with the existing races changed into castes?
I.e. instead of having a race for every animal man you want represented, make grand alliances of multiple. I'll give three examples.
Instead of one civ each for Alligator men and Saltwater Crocodile men, you have Crocodillian Caliphate, with males and females of the two species making up four castes in one mega-race.
Instead of Leopard men, Cheetah men, Bobcat men etc., you have the Big Cat Brotherhood of all of them, with however many castes are needed for males and females of the chosen species.
Instead of fox men, dingo men, wolf men etc. you have the Canine Confederacy.
If it's done that way, world gen will be more managable from the lower number of possible civs.