In the latest preview versions there are several issues with texts in Cyrillic. They are most likely fonts issues, but I have not found where I can change the font.
Cyrillic notes are not cursive - http://take.ms/fByEC
Bold text of project name is bigger in Cyrillic - http://take.ms/OApbN
Cyrillic list item text is slightly bigger - http://take.ms/E3nnd
Tags text in Cyrillic is slightly bigger too - http://take.ms/bBUq4
These issues are not reproduced in the TaskPaper 2.3.2
Here is the test text in Cyrillic which I used, so you can just paste it.
Some project Проект:
This note in English is cursive.
The following line is a note in Cyrillic, and it will be not cursive
це нота кирилицею і вона не набрана курсивом
- tasks are ok in English
- but in Cyrillic the font is slightly bigger ось як він виглядає
- а тепер окремо
- what about @tags
- tags are ok in @English @Кирилиця
- in Cyrillic they look @інакше