I am confused. Returning to your sample project I have now added these two lines to VA's StdAfx.h file:
#define INTERFACE_MIXIN(INTERFACE_MIXIN, DEFAULT_IMPL_MIXIN) template<class TBase> class INTERFACE_MIXIN
#define IMPL_MIXIN(MIXIN_CLASS, INTERFACE_MIXIN, REQUIRED_EXTENSIONS) template<class TBase> class MIXIN_CLASS
and after a symbol database rebuild none of the classes in "test.cpp" are being underlined by VA as mistyped symbols.
If you have lots of classes using the same two or three macro's then we just need to find a suitable work around for the macros and this should fix all of the classes in one go.
If you have a large number of macros then I can see how this would be more of a problem.