Hi,
I tried Kindle viewer and it looks fine - attached.
I've also attached a text version of input RTF. If you apply correct font, it looks fine on all viewers.
The problem as you've pointed is encoding. This is old Slavonic text; there are plenty of websites and they all only displayed correctly if you have the right fonts installed. They are compartible with each other.
Easiest format to read is PDF with embedded fonts; it always looks right on all devices.
I'm really keen to use native Kindle format instead of PDF...
Some encoding symbols can be seen here, I have not find a better explanantion of this encoding.
http://www.fonts2u.com/orthodoxtt-ucs8.font
Thanks a lot for your help.