My understanding is current US sanctions against Cuba penalise...

My understanding is current US sanctions against Cuba penalise companies with a majority interest (>50%) in Cuban business ventures. AAU can operate because they have 49% interest.
You ask if Cuba can still trade with Russia if US sanctions are imposed? Theoretically they could but the point is AAU could be subject to penalties (fines, imprisonment of staff) if the 'severe sanctions' Biden has promised are imposed. The sanctions would be trying to stop Russian trade.

I also have not changed my investment in AAU because I purchased before talk of Russian sanctions arose. But I have not bought more because I am waiting on the scoping study to see the strength of the investment analysis and to see how sensitive it is to an increase in the smelting charge that is likely if sanctions are imposed on Russia.