Angor said that just to look serious, in fact, he had no idea what kind of test to give the kids yet. He just didn't want to tell anyone that he urgently needed one more new recruit to finish his task.
Since this was decided, he planned to get to it eventually.
In Vonman and Guina's case, they had some problems with their manners and the way they treated other people. Angor didn't intend to teach them how to behave, but he had to at least make sure the children didn't offend someone in the wizarding world as soon as they got there and got killed by it. Especially Vonman, who appeared to be rather imperious.
He could come up with a proper test quickly enough, but he wouldn't do it now. Before proceeding further, he had to ascertain the nature of their talent first.