And do I need to write any specific line/s of code in order to do that?
**Sorry, just kinda new to RenPy here ^^
The latest update on GitHub makes GUI display text use DejaVuSans explicitly.
Basically,
# BEGIN STYLE
style game_status_text is text:
font 'DejaVuSans.ttf'
color COLOR_WHITE
size TEXT_SIZE
style promotion_piece is button
style promotion_piece_text is text:
font 'DejaVuSans.ttf'
size TEXT_BUTTON_SIZE
color '#aaaaaa' # gray
hover_color '#555555' # darker gray
selected_color COLOR_WHITE
style flip_board is button
style flip_board_text is text:
font 'DejaVuSans.ttf'
size TEXT_BUTTON_SIZE
color '#aaaaaa' # gray
hover_color COLOR_WHITE
# END STYLE