Sorry, you misunderstand:
The headlight washers don't work in the headlight auto mode (leftmost position, headlights with an A). To get them to work he apparently has to switch to non auto headlight mode. In that mode high beam assistant won't work. So it has nothing to do with the high beams themselves being on.
His problem as I understand it is that he can't drive at night using the high beam assistant and get head light washing. This is an issue at night on dirty roads (which we get in sweden when the roads are sanded and salted to prevent icing conditions).
