Thanks for sharing your experience!
It sounds like the problem you are having is a low brew temperature on your Robot. I use a Picopresso, which is also an espresso brewer where you add heated water to the brewing chamber. The problem with these kind of brewers is that it's very hard to reach temperatures necessary for light roasts. I could hit about 95 degrees celsius once but only after pumping through several loads of hot water and insulating the brewing chamber.
I also like medium and dark roasts so I only take those with me when using the Picopresso. Those work really well and are easier to dial in than light roasts.

High quality powder milk! That's what we use on the boat exclusively with the belman steamer (paired with Robot).

Any to recommend? What makes a powdered milk high quality?

try different brands, I'm in New Zealand so my recommendations would be useless. Some are better than others. But you'll find one that does the job.