I think they were just trying to find common ground to start the process of correcting them, the same way I might tell a unitarian, "hey, we believe in the same New Testament" to start a conversation that leads to me teaching them the Trinity. Maybe not a perfect approach, but not heresy.

I think the modern understanding of extra ecclesium nulla salus is the closest V2 gets to heresy but I've read enough older declarations and letters that I'm comfortable with the language they use. If you want to attack V2, though, that would probably be a more debatable point :)