As I didn't learn Japanese with a translation in mind, unstranslatable expressions are still untranslatable in my head, but I still understand them... Particles are tough, but then again, Japanese nationals don't have them down pat either, so I don't worry about that overmuch. I simply cannot katakanize words... But then I can pronounce karaoke or sushi English style either... As for the other stuff... I'm sure there is, but I can't think of any at the moment...