You want to isolate problems, not to go with some trial and error in your enormous project code.
In a totally empty sketch, set up necessary library to use the LCD to display the phrase that would be displayed wrong in your project code, will it be displayed correctly? Your code space is 1K from being filled so unless you have practiced extreme measure to save SRAM space, you have run out of SRAM long ago.
When wrong characters are displayed, is your project still respond or run as expected?