Firstly, you could like to know that you need to post just once. Your post will be visible just after accepted by a group moderator, so you need to wait. It is needed to avoid spam.
Concerning your request, it is not a matter of simply "adding some Cyrillic fonts". Picture to People supports more than 30 languages as stated at the How to Use page, and it is enough for most of our users (http://www.picturetopeople.org/how_to_use.html
Supporting other languages requires UTF-8 encoding, what impacts a huge amount of code (TTF, decoding, string, composing, rendering, etc). This site is made using version 1.1 of Picture to People computer graphics libraries, and such version doesn't support UTF-8.
I am developing Picture to People libraries version 2.0 with UTF-8 support, but, when they are ready, I intend to use them in other projects. Since the Picture to People crowdfunding campaign failed, I am not focused on adding new features to this site anymore.
In short: no, I will not add Cyrillic fonts, because they will not work on the site anyway.