Well all this concerning safety of different types of glue is really worthy a whole thread of its own - lets not hijack this one :-)
In general though, it can be said that eating the glue is of course normally not the greatest issue ;-)
I'm more concerned about skin contact and breathing the fumes (that can oftent not be smelled before it reaches concentrations way above recommended max).
I'm certanly not "religious" about the topic, but I am concerned about health and try not to expose myself or others to unnecessary chemicals.
But we can discuss all that in another thread if you like ;-)
Anyway - There are definitely lots of glue-types that work well for horn nock overlays - In my experience most glues work fine, as long as you clean up the surfaces first.