Hello, TFTLCD library suffers from problem that Aduino ui, uses only utf-8 caraghter set for strings. This is bad because most fonts for microcontrollers are 8bit fonts using cp437 or MS-DOS caraghter set to display font. It would be wise to develop into arduino CP437 codepage support instead only utf-8. Since all atmel microcontrollers use bytes to send and receive, we need to use 8bit font. Since extended Ascii has more special caraghters meaning you could print 128 letters more. CP347 is on of the 8bit font code pages which is mostly used with LCD fonts atleast in TFTLCD and Adafruit TFTLCD.
Using utf-8 here makes too much space usage as PROGMEM because 16bit fonts versus 8bit.
The thing where current IDE fails is that ascii is subset for utf-8 but extended ascii is not. Thus IDE should be able to switch into MSDOS cp347 caraghter set, in order to provide string encoding in extended ascii and able to draw special cargahters correctly.
Also if IDE could have 8bit codepage support then those special letters could be displayed in Serial.print also without displaying weird caraghters.
To add more, arduino ide should switch using 8bit codepage to utf-8 when changin board. If using DUE till example, strings would be handled as utf-8 and when using 8bit boards, use 8bit MS-DOS codepage.