That is factually incorrect. Cavill wanted them to be more faithful to the books, so they changed from the monster of the week setup of the 1st season to the silly political drama of the books.

The thing about The Witcher is that the books aren't very good. People like the Witcher despite the horrible writing (the same way people liked Twilight despite the horrible writing). If Season 1 had been faithful to the books it would never have taken off.

Most people seem to be basing their ideas for what the show should be like based on what the games were like, but the games are quite liberal in their adaptation of the underlying material.

Can you share any source describing that Cavill had the most influence on season 3 out of any seasons? Right now it's pure conjecture on your part and goes against what Cavill and others said themselves.

Complete Nonsense. The whole Witcher series is very well written (though I read only Czech translation, so I cannot speak of the English one) and Sapkowski is a good writer (which he later more than proved with The Hussite trilogy). The problem with the second season is that they completely butchered the story from the books. If Cavill wanted the series to be more faithful to the books, he failed.