1) go to assets/minecraft/optifine/cem and look for "head_skeleton .jem", 
   and then rename it like "(((head_skeleton))).jem" or something

2.) stay in assets/minecraft/optifine/cem and switch the "witch.jem" and "witch 1.12.jem"
    to "witch 1.14" and "witch.jem"

3.) follow the step 1 instruction on the "horse.jem" file


4.) slimes and magma cubes dont work properly, so just rename it like "(( mob name )).jem" or something


5.) if you change your mind, or wanna return to 1.14 optifine, follow step 1-4 BACKWARDS



the mob variations wont work properly on 1.12, but fuck it, 
i'm pretty sure all the servers have updated to 1.14 or something