Sounds like your update didn't update properly. The functions are no longer needed or used as registration happens per terrain during OnEnable, and OnDisable. So these functions have been removed, and no CTS code refers to them.. ergo you should not even notice they are gone. Save data, delete CTS and re-import. We successfully tested compiles and builds of CTS on latest Unity 2018.2.6 plus .Net 4 & ECS. It was however very late when i made code merge and release build and I may have messed this up. If this does not resolve then let me know.