The information sheet pertains mostly to the headlamp unit. It doesn't seem unfeasible to retrofit manufacturer made xenon units (as some 159/Brera's had) in order to comply at least in part with the regulation - the stipulation that they must be ECE98 marked
As for the additional requirement for cleaning and self levelling the information sheets states the vehicle should be able to reach ECE 48 standard but
when fitted to the vehicle should enable ECE Regulation 48 to be complied with (although no government inspection will take place);
Presumably the anticipated inspection might have been an independent examination of one of the vehicles concerned. I wonder if this becomes an overarching principle when original manufacturer made xenon headlamp units are installed. (IE, if it's a manufacturer made unit then no inspection will occur)
The requirement for washing and self levelling does seem to be important, but I wonder when an examination of those features would take place - certainly not at the MOT where only beam pattern is concentrated upon.
In terms of a police stop,most police officers will be satisfied if the headlights are not causing an undue hazard to other road users. That leaves roadside VOSA examinations. We do get a few of these in my area each year (chavs in Corsa's with wheels so big they rub the wheel arches), but they only inspect between 9-5, Monday to Friday here.
My personal view is that while the information provided by the dft is well intentioned we don't live in a state where the intention of government is to insist on compliance with every law where someone seems to be going about their business in a reasonable manner. At the worst I think if a police officer wanted to, and in force areas where vehicle defect rectification schemes are still operational, then the worst that can happen is that yoiu will be asked to change back to standard bulbs.
I cannot see a day when any member of the CPS would consider wasting expensive court time on someone who has merely 'accidentally' fitted what some consider to be incorrect lightbulbs. If the driver says "I had no idea, thanks for bringing it to my attention, I will now make necessary changes" then that will be the end of it.
As further precautions, if the driver carried the original bulbs in the glovebox (not as a 'just in case' precaution, because that is almost like admitting knowledge of an offence, but simply because they had forgotten to dispose of them) then the driver could put up his hands, suddenly 'remember' he might have the original bulbs in the glovebox....and when the courts are full of people who implanted a beer glass into a stranger's face i doubt a court appearance, nor even a fine would ever be issued.
Remember, laws on scientific matters are rarely made by scientists....manufacturers are responsible for certifying their own eqipment, so a member of public who rightly believes he is improving his own safety by fitting HIDs and takes enough care not to affect others when they do so, isn't 'satan' in the eyes of the law.