I want to figure out the more advanced parts of animating an entity, but the vanilla model class files don't seem to exist for reference. Which package are they in?

so I tried the thing you told us to do if the ad blocker wouldn't work and I did it so I double clicked ti then this came up “forge-1.12.2-14.23.5.2854-installer.jar” cannot be opened because it is from an unidentified developer.      then this  Safari can’t open the file “forge-1.12.2-14.23.5.2854-installer.jar” because no available application can open it.

Looks fine.

I've done 2, 3 and 4 from the list atm, but I dont know if this alternative for the transparent glass is appropiate.      

here On the other problem I tried what you said and it had no effect.