You dont have spongeforge on your server, therefore its another mod causing your issue. What that mod is i cant tell as normally there is a .json file with mixin errors that tells you what the mod is but i cannot see one.
Your best bet is to remove each mixin mod to find the culprit. You can do this in a binary search style where you remove half your mixin mods, if the crash continues you know its one of them, if not then you know its the other half.
I have a program that will show you all mixin mods installed on your server called Mixin Detector Program