Oh I see - yes I did misunderstand, sorry. It's difficult to say, really, if you aren't told how much sugar they are using. What you can do is look and see where it comes on the list of ingredients - they should be listed in order of quantity, so if it is way down the list then there wouldn't be very much.
In any case, if you are only eating the shallots, and not swigging the vinegar as well, I wouldn't think you would be taking on board much of the sugar. Personally, I wouldn't worry about it.