Unicode/Cyrillic problem

[MarSoft]

My system: Arch Linux, Wayland/Sway WM. Installed d-tracker v1.4.r1.gafdeafc-1.
Locale is ru_RU.UTF-8.
When I try to enter Cyrillic text to the app, I get unreadable text, aka tofu, aka squares: https://i.imgur.com/rRP7lAt.png
Most likely it is related to fonts, but I could not find out how to change display font. Only color themes could be changed.
Is there any additional information I could provide to help solving this?

[drmargarido]

Under windows I set the font because the default font was not readable.
Under linux and the X11 backend it should use the system default font.

Fonts can be changed in the themes, here is an example on one of the base tekui themes ->

d-tracker/external/tekUI/tek/ui/style/industrial.css

Line 47 in 7f00cc9

font: sans-serif,helvetica,Vera:18;

Try to change the fonts in the current theme you have active and check if it solves the problem.