Problems with Bitmaps on TFT Display using GFX Library

Other Hardware Displays
2

You have declared the array as in SRAM

//Main bitmap images stored in Bitmaps.c
extern uint8_t MainTFTDisplayBitmap[];  //Main Background Image

add the const qualifier and it will use the correct overloaded drawBimap() method:

    //bitmap in PROGMEM
    drawBitmap(int16_t x, int16_t y, const uint8_t bitmap[],
      int16_t w, int16_t h, uint16_t color),
    //bitmap in SRAM
    drawBitmap(int16_t x, int16_t y, uint8_t *bitmap,
      int16_t w, int16_t h, uint16_t color),

David.

Edit. Your bitmap uses 2560 bytes which is not too expensive.
However you could probably draw the lines and print the text with regular GFX graphics methods. It depends on whether you are using that particular font elsewhere.