It seems like they were in a rush to replace the missing wizards, so I can understand why they couldn't be too picky about their choices...

Maybe it's just about whoever's able to take to this world's magic. It would be pretty pointless to end up with someone who couldn't communicate with the spirits he mentioned.

[Unless anyone they summoned would be able to do it automatically? Honestly, it's hard to sort out cause or effect here when they don't know much about how this world works.]