Make sure that you have "Gulim" font. OpenRCT2 uses that by default.
If you do not have that font(linux, macos), you have to edit config.ini's font section.
file_name = "NanumGothic.ttf"
font_name = "NanumGothic"
x_offset = 1
y_offset = -2
size_tiny = 11
size_small = 12
size_medium = 12
size_big = 13
height_tiny = 12
height_small = 14
height_medium = 14
height_big = 16
(You need to install NanumGothic)