It also has to be enabled on server side with g_dismember afaik. And seems like you should try values between 0 and 100, that controls probability of the dismemmberment where 100 is 100% probability (according to the game code). And cg_dismemeber (client side) could be 0, 1 or 2, and when it's 2 then it also slashes head and torso.
If you are trying a patched DLL with not patched engine (EXE) then it is the problem. Either build and put patched EXE next to your DLL and don't forget to get official assets that come with the official game patch 1.01. Or build not patched DLL and not patched EXE. Here is source for 1.00 (not patched): https://github.com/jedis/jediacademy/tree/e0610d49dd24880794b25c3c644df58a73e4a6e5 Your error comes from the engine, by the way: https://github.com/jedis/jediacademy/blob/e0610d49dd24880794b25c3c644df58a73e4a6e5/code/server/sv_savegame.cpp#L1875