As of now, many of you have probably noticed the broken head models from the Skeletons 505 and Creepers 303 resource packs. The problem with these blocks, is that the model is not a simple json model like other blocks of the game. The heads are tile entities like the chest and sign. Tile entity models can be changed through Optifine but not all of the heads are supported, and we are working to figure out the best way to solve this. This is not to criticize sp614x's development of the modification, since they are a very busy person and we are happy to work around when they make updates. However, this means that the heads may not get fixed for some time, unless we are able to fine some way to fix them that already exists. Thank you all for understanding and appreciating our work anyway.
-Voyde Team