The resident protection drivers do support Unicode, i.e. they won't allow you to start an infected file. However, the "higher" functions (display, actions, ...) are still mostly ANSI - so, they require a matching setting of the "Language for non-Unicode programs".
Recently (= after the build 652 was released), I did some improvement, regarding the On-Demand scanning, and I plan some more in the future.
Btw, do you say that when you change the language for non-Unicode programs setting, the programs change their interface language? I wouldn't expect that...