Chromatic Abberation is usually seen as "color fringing" at high contrast edges in the image. Think a black moose on a snowy background. At the edge you will see a shine of color, usually purple or yellow. It is the result of white light "dispersing" (splitting) into the primary colors when it passes through the objective lens. the result is the CA lowers contrast and apparent resolution.
Although it can't be fully corrected, there are a few ways optics designers deal with this issue. The most common is the inclusion of flourite in the glass composition of the objective. Glass with flourite (or other similarly performing substances - like lananthum) disperses light a whole lot less. Companies market this kind of glass using whatever term they want like ED (extra-low dispersion), HD (High Density), APO (apochromatic), FL (flourite) or others but they all refer to the same thing in sports optics.
Kowa went so far as to use a pure flourite crystal lens in the objective assembly of their awesome 88mm Prominar spotter. When I have looked through this spotter in a number of situations, I have never been able to detect a hint of CA.
The Zeiss Dialyt and non-HD Swaros use standard optical glass, and although their images are still really good, they do show noticeable CA. the ED50 corrects for CA very well, which is one of the reasons why it provides such a great image in such a small spotter.
Now CA bothers some, and doesn't bother others. I see it easily and find it annoying. The human brain can ignore CA pretty well, and look through it to see detail. People that don't see CA much are usually happy with non-HD/ED/FL glass. The camera always sees it, however, so if your digiscoping HD/ED/FL becomes more important.
Hope that helps.