This web page may be of interest to you.
http://sound.westhost.com/lamps/elect-trans.html
Others are having the same problem as you when trying to measure these things. I personally would use a portable Oscilloscope to view the waveform. This may seem total overkill but in order to know what is going on in a PSU circuit you sometimes need to see the shape and behaviour of the AC waveforms. A multimeter is sometimes not enough as it can miss-measure a complex waveform. Modern 'low-energy' lamp drivers are even worse ... with timed start up voltages, running voltages and current monitoring by a clever IC...but thank goodness they are throw away items !
Looking at the waveform in fig 3 in your link You are looking at a high frequency and modulated output that is not very uniform so I'm not surprised that a DMM is having trouble taking a reading.
You would need to rectify and smooth the output to take a DC reading and you will need to use fast diodes etc, thats more than I would know how to do or would be sure I have an accurate reading.
These "Electronic lamp PSU's" are often hidden in building structures and have limited if any air flow, they only have a short life if covered with fibre or building insulation I think.
An electrician would just swop out a bad unit no voltage test needed its the most cost effective way. I have seen 70 to 100 of these put in a large 5 bed house and as a maintenance procedure it would probably be better to change the lot when they start to fail, otherwise you will be back many times as each unit reaches it end of life.
A large house that had halogen 12V lamps installed had large toroids to power the lamps in the hall, with a long run to the basement location of the toroidal transformers. It needs large high current cabling as well on the load side, a better job IMO and more reliable but still expensive.