Post-Sputnik America thought it needed to "catch up" with the Soviets, to beat them in space and science and weaponry. Most of the students taking Russian were anything but Communists. A lot of them were science geeks who figured they needed to learn the language, or else snobs who looked down on Spanish and French classes. I don't know specifics about the UHawaii program, but most of the Russian language teachers in American colleges were Russian emigres who were not sympathetic with Communism.
Ann and Barack Sr. sympathized with the Soviets. Yes there were the scientists and such but you can bet the FBI was watching Barack Sr. and Ann.. They were indeed watching another member of their circle, Frank Marshall Davis.