There are few facets here.
(1) Poland after decades of forced socialist regime and building communism by USSR in it, simply had NO law protecting intellectual property
rights after transformation. And you would do yourself a favour reading a bit about CDProjekt beginning. At start they were benevolent 'pirates' in a 'wild west' state. However, when finally proper legislation was passed, they did not continue (like other companies) to try and pirate things regardless of the fact that it is illegal or close down shop. They reformed their business and tried to continue becoming one of the first publisher's in Poland. Approaching western game industry companies (ie. BioWare) and asking if they can localize and sell their products on this rather hostile market to foreigners (raging piracy, common people were still getting their games illegally). So in short they were avid gamers, that after being pirates, became publishers and later on opened studio to start creating their own games.
(2) After the chaos at start, state went a bit overboard with regulation and protection. Enter clause 44. But you would need to understand what sort of mob controlled, corrupt and violent state was Poland in '90s of previous century. People were (and to a degree still are) demoralized and hostile towards their own state - that is natural after atrocities of communism and iron rules of the Party.At start there were illegal TV stations, radio stations, 'publishers' (books, games, music you name it - yes they were just copying it all without any fee for authors). After these became illegal, mafia took over and continued. It took another half a decade to eradicate that. If you ever had any dealings with organized crime you would know that they do tend to pressure rather efficiently legal deals that are not in favour of non-mob party and it's nigh impossible after, to prove in court that this were due to series of unfortunate events that happened to the pleading person, not just because they 'changed their mind' now. It was 'easier' to construct the law that if there is discrepancy, there is valid claim, judge should evaluate.
(3) Sapkowski is a petty man. He's a 'hard leftists' that is a 'sexist'. He's 'a tough guy' with physique that would let 12 yo girl to beat the living shit out of him. He is rabid entrepreneur, that hates capitalism. He tries to be 'smart guy' but ends up making decisions that lose him tons of money. There are heaps of anecdotes about his overblown ego and you can probably just google and dig up few brow rising quotes about his own books, fans, video games, people etc.
IMO he is an ever unhappy man, that now became a bitter old, grumpy gramps, who his all live concentrated only on everything negative around him and every little depressing and 'unfair' thing said and done to him but ignored everything he had, achieved and created and all positive things that came his way (cautionary tale to the lot of you youngsters btw).
(4) Sapkowski is a brilliant writer. He had not created a lot but you should give a try 'Hussite Trilogy' at the very least. Not just the Witcher. Perhaps that's a lot due to his flaws and quirks and overall 'douche-baggery'. Perhaps he writes and puts on paper things he always fails to articulate interacting with people. Only thing that matters here is that you should separate evaluating man's character and his works/deeds.
Having said all that. Likely CDPR will settle with him. Not for that crazy pile of money but still. Judge in court is likely to destroy Sapkowski's case, even though he has 'valid' claim and 'humiliate' him. I doubt CDPR would like that for this 70yo, about to kick the bucket, goblin. So if he isn't going to be stupid about it - yet again - he'll get few millions out of it.