[Coda]

Should have been は instead of わ but I'll chalk that up to a typo, and usually you use れんしゅう for "practice". (If you're using the dictionary I linked, check the "commonly used words" box. It helps.) What you said, assuming those changes, was "As for us, practice is Japanese."

You could have said "nihongo no renshuu" (literally, "the practice of Japanese"; in context of the question that was asked ("what are you doing?") it would be "Japanese practice.") and you would have been satisfactorily correct. "nihongo wo renshuu suru"/"shimasu" would be "we practice Japanese" (or "shitteiru"/"shitteimasu" for "we are practicing Japanese") would have also been acceptable.

Good try though :)

Edit: *checks dictionary* >.> Whoops. Your "gakushuu" is perfectly valid for "study". ^^; It's marked as "common" although I would have probably used "manabu" or "narau".