The Russian GM would obviously know what the imbalances are, but just not heard the phrase. He would know when pieces are strong, if a player has weak pawns etc.
Every chess player knows imbalances, it's just to what extent and how well they can analyse them to formulate a plan.
Some people think the constituents of a position are Space, Time, and Harmony, instead of Minor Pieces, Squares/files/diagonals, pawn structure, material, space, and initiative....Some say King safety, pawn structure, piece activity.
All are ways of evaluating in a systematic way what the chess board looks like, and giving you a recipe to form a plan with. And yeah, pretty much all 1800+ (OTB) players will understand positions in some form, but they may not call it "imbalances."
I think even 1500+ players knows imbalances like faster development, material advantage etc etc .....
At below 1600, it takes some training to understand where they are. Once you get higher-rated, it becomes much more natural.
Imbalances can be learn through books, and by your own games.
"Improve Your Positional Chess" by Hansen talks about this topic. :)
You've got to understand the concepts at some level, even if you don't use exactly the same terminology or thinking systems as Silman.
Bishops vs Knights, space advantages, differences in material, open files, taking the initiative etc. all form part of Silman's "Imbalances Theory" (if I may call it that). These concepts are not foreign to Master class players. Silman simply does a break-down of these concepts and presents it to us patzers in an "easier to understand" way.
He could have called it the "Silman theory" for all I care. I love his books! 
Am reading thru a couple of good books by Jeremy Silman. He's always talking about imbalances - 2 bishops vs knight and bishop, space advantage, intiative, etc. and how you must try to take advantage of them. Do all 1600+ players know about this? and to try to take advantage of the imbalances? or do some look at other things instead?