Could you please consider changing the font for the russian course? It looks very unorganic and reminds me of font used on countrafeit electronics/wares.
I disagree with you on the Latin font—I find it extremely hard to read, with major problems like the letter 't' being shorter than all the other middle-height letters, and letters with hanging parts like 'g q y' getting clipped off in lessons.
The problems are so serious I think they can't be universal, perhaps I have an unlucky configuration or am in a test group. I have read some complaints from other people in the forums, but they are usually buried under the (equally-valid) suggestions to change the colour scheme to also reduce eye strain.