I do not want to clutter the discussion of incomprehensible code (in addition, the comments in Russian), so provides examples of pieces.
I uploaded the library with main project on github: GitHub - Maratk1n/cheesemachine
In the ITEADLIB_Arduino_Nextion-master directory is a modified library for the display. In file NexHardware.cpp I changed the line 19, but the display is completely stopped working. But it compiles without errors or warnings.