Turns out a relatively important plot point in The Witcher games shouldn't exist at all, so says the books' author
The thing about an adaptation, is that sometimes you've got to twist things slightly to better do what you want to do. Whether that's the right choice or not depends on how militant you are about the concept of faithfulness. When it comes to The Witcher series, however, I expect most people won't care, except for the author of the original books Andrzej Sapkowski himself. His personal gripe? The very existence of different witcher schools.