Oprindelig tekst - Bulgarsk - dobar ve4er bih iskala da pora4am pile s kartofi...

This is Bulgarian, not Russian.

разменени са езиците - това е на български, а не на руски.

What does that 4 stand for?
What letter would that be?

CC: galka ViaLuminosa

Casp, this is CH, as "church", 4=CH.

Hmmm, now that makes sense. Looks like that cyrillic "ч"
But...do you guys write like that, or it's just a substitute to another character?

No, no Ц, but Ч!

Yep. A bit sleepy here. I had already edited before your correction.