"vaktali" is an old word, probably Old Norse, it isn't used anymore. IMO it's not the same as guardian. As the text says, it exist in "ritmálsskrá" but without any example. When reading "ritmálsskrá" there is actually one example, it's from the bible "Exodus 16:13" from there I understand that "vaktali" is a quail. In Faroese the synonym is "vaktil" which means quail.
I would say to change the source text. Change "vaktali" to "verndari" what do you say?
Oh, when I did this translation, there was NO example in the dictionary, they must have done an update. I guess the requester asked for this translation just because there was nothing to find earlier. So, I’ve misunderstood the source again, sorry for that.