Candy syrup or candy sugar (usually named “candi” sugar) is a fancy name for beet sugar that has been caramelized into syrup with a dark color and rich flavor. The flavor of candi sugar is definitely rich and I can understand why brewers use it as a source of fermentables and flavors. I personally have used dark candi sugar in Belgian-style dubbels and the beer turned out great. However, I honestly don’t know if the candi sugar added color or flavor since I used special malts for the most obvious contributors of flavor.The instructions you describe above have a few details that I question. The first detail is the suggestion of adding the sugar at two different times during the boil. The candi sugar has been caramelized during the manufacture and I do not believe there is a need to boil it for a long time. Also, since browning reactions between sugars and amino acids are favored by higher pH levels, there is really not much browning or caramelization that is likely to occur during boiling.
I would add the sugar towards the end of the boil to make sure that it goes into solution and that it has been exposed to heat to kill anything that may be on the surface.The other detail I question is adding the third portion to the fermenter. While it is true that yeast do metabolize sugars differently and that having too much of these easier-to-metabolize sugars can lead to stuck fermentations, my experience leads me to believe that this is not something that should be a major concern. I would be more concerned about expecting ale yeast to ferment sugar added to beer that is aging at 10 °C (50 °F). I suggest simplicity unless something more complex is warranted. The type of beer you want to brew is one of my favorites when properly brewed and I think you will be happy adding all of your sugar in one addition towards the end of the boil.