After tinkering for a couple days I have everything working with the addSubstitutionAlias method. So I started substituting blocks and ran into the odd limitation of only being able to substitute 19 blocks. I wrote this test/example code to show the problem. Sure enough, if I substitute 19 of the blocks it works great. Add a 20th substitution and I get java.lang.NullPointerException: Initializing game. I also tried the code in the latest 1.11.2 build and got the same thing.