This could be simply a setting in the cluster menus, setting the headlamps for Continental driving i.e. driving on the right? Maybe someone has had a play around and accidentally change it?
I'm curious about the "Lexus importer". Did you not buy the vehicle through a UK Lexus dealer? In which case the 'import' isn't actually an 'import' in usual sense of the term, where one purchases a car from a dealer outside the UK and arrange delivery to the UK. I take it you are in the UK?
The first link I posted is the official Lexus EU technical document repository and one has to register and pay to access the detailed information, (well worth the few euros it costs IMHO) lots of detailed info on your specific model, as one enters the vehicles VIN. I think you'd be well advised to explore!