I read the "syrups" to be like the sugar-free pancake syrups. I think anything in this artificially sweetened/no nutritional value category should be counted in the 75-100 calorie "sweet treat" limit, so the Torani/DaVinci syrups wouldn't count anyway if they have no calories.
I don't think there is any limit per se on artificial sweeteners, just moderation. I personally would love to get away from them altogether but there have been times that something artificially sweetened has saved me from going off the deep end
So yes, they can be quite useful.
BTW, there are some Phase 1 mock pancake and french toast recipes that would be good with a SF pancake syrup! I often make pancakes from eggs/egg whites, grated cauliflower or zucchini, and a little ground flax seed (I think 1 T is permitted on Phase 1?). I don't know of a good syrup to recommend though. I bought one, which turned out to be almost 100% malitol, which does NOT agree with my belly