Gold Wizard: "These are Beastmen/Greenskins, their lives are insignificant."Those are the tame Chamon Combat spells. I don't even want to guess how a Witch Hunter would respond to a spell like Gehena's Golden Globe if they understood the difference between it and a Final Transmutation. The difference being that for a Final Transmutation a Gold Wizard has to just believe that he will end the life of their opponent(s), for Gehena's Golden Globe the Gold Magister has to believe in the insignificance of their enemies' lives. And Gehena's Golden Globe is the upgraded version of the Final Transmutation.
Witch Hunter: "They are Beastmen/Greenskins, kill them all."
When it comes to the enemies of mankind, their views aren't exactly incompatible.
But while the Witch Hunters will always be twitchy about magic, the Amber integration issue lay with the soldiers and officers. Specifically casting mind-altering spells on allies without warning them.
The average soldier doesn't really care about what the Wizard is thinking(as long as it isn't heresy). And watching your enemies die by things you don't really understand? Well, the average soldier doesn't exactly understand how a gun or doomsphere works either but they kill Beastmen real good.
Having your sword grow unnaturally sharp is a lot less freakish than suddenly turning feral and losing control over yourself.