The biggest obstacle for the Poles in understanding Russian is Cyrrilic alphabet. We the Russians don't have that obstacle for everyone can more or less read Latin letters.
Being nowhere constantly, we have equally relevant two alphabets (East, West), one is taught in the 1.grade(cyrillic), the other one in the 2. grade (latin) of elementary school.
My education in large part was happening during the golden liberal socialism period, when different elem. schools had two different obligatory languages. English was the most common, and present in almost all of the schools(95%), second one was russian, then close to the oldest part of Belgrade, as a second language instead of russian that was more common in Novi Beograd, German and French were taught. Kids could choose only the school, but not the languages they will learn in particular school.
Summary: I had 5 years of English, from my 9- 14 year (most basic level), and in gymnasium my foreign language (elementary school was determining that one) was only russian. English was replaced with Latin.
Problems I had with Russian are not describable!!, we all mostly cheated shamelessly, my lexical fund was enriched with, all in total 20 truly russian words during 8 years of 'learning' it.
Russian grammar , on the other hand, I knew better than Serbian. System was for some unknown reason insisting on knowing by heart all declinations for nouns, adjectives. (in Russian)
So, I have no idea how would all that look like if there was no russian in school, but I do understand approximately 70 % of spoken russian, and I know that Russians understand me proportionally.
Written Polish is harder for me to comprehend than spoken one, and I understand it even then far less than russian.
I found the link to that chart, I am not sure about reliability of the source.