I was really surprised to see that because there are no Russians in POV dev team, and even my Steam client is set to English! Alas, the writing doesn't match the wall size but is still funny)
This is right after you exit the garage where you battle dark delta troops, see Gman Looking Down (chapter 22 of the Story) and find 2 cages of snarks in delta troops' truck.
It says "...of world Xen. ?We shall blow you all up to the medieval era(literally "to your mother")" in Russian
I was really surprised to see that because there are no Russians in POV dev team, and even my Steam client is set to English! Alas, the writing doesn't match the wall size but is still funny)