If you speak Russian or Serbian, or Macedonian or Bulgarian for that matter and cannot BASICALLY understand Slavonic Liturgy then I don't know what to tell you. Maybe you're slow.
Now that's a really Christian attitude if I've ever seen one! Many Russians I know, where Russian is their primary language, do not understand Slavonic. In my former parish, when the Otce Nash was sung in English, the entire congregation (all of Russian or Serbian descent--some first generation) would sing. However, when the Otce Nash was sung in Slavonic, one could hear only the choir, and maybe a peep from the congregation. I don't think that this congregation of engineers, doctors, lawyers, and regular folks were "slow" just because they didn't fully understand Slavonic. I think it's more like expecting a person fluent in Spanish or Portuguese to thoroughly understand Latin--yeah maybe somewhat, but it is still a different (archaic) language.
Thank God for Sts. Cyril and Methodius who translated the Greek services into an idiom that was understood by the people of that time, and thank God for St. Innocecnt who translated some of the services and writings into the native American tongues. These men, believing that the Orthodox Church is THE Catholic Church of Christ, acted with a sense of mission to bring all peoples into the true Church and to pray in their own languages (to the tune of 1 Corinthians 14)--unlike the Roman Catholics with their dead Latin and the Islamists with their Arabic.
gbmtmas