It is a PVA type glue such as Titebond, Elmers white or wood, and a multitude of other glues. I have not used it myself, although I have looked at it before. I am not a luthier. The linked data sheet spells out the composition pretty well.
The 190F "problem" exists for all PVA type glues. Incidentally while the glue joint is weakened it regains strength when it cools, if not actually broken. In this case I am nearly positive that "separates easily" means "the wood is much stronger than the glue".
I do not know if some percentage of strength is lost after heating and later cooling, only that the glue will became stronger than the wood I was working with at the time. I was not using the linked glue. I do not know the brand that was used, but would guess Elmer's wood glue since it was a high school wood shop project.
I was referred to this product previously because of the bottle. It is supposed to be very nice, but I don't have one of those either.
Phil