The problem is that the author abandoned this game many months ago. And I don't think he wants to do anything in this direction.
I feel like there is some confusion. Let me give me info from the start, in one whole chunk and hopefully clear up some confusion.
I played this game (the version offered in OP here). I got to end at the ciri battle and could not win. I read through posts here and on the devs discord and saw this was a common(ish) error. I asked the dev about it and was told that I was having those issues because I was not on the latest version. He told me the latest version was on his patreon (it is a newer version than what I was on, I dont remember specific version numbers or anything, its been a few months). So my options were to sub to his patreon to get the update, or keep trying to beat the fight (others have succeeded, so there is a way). In the end I just stopped playing it and never got the newer version.
I did however submit a "report" on the OP stating that there was a newer version per the dev (I was told this is the best way to inform OP that there is a new version). I never received a reply but it does not look like an updated version has been posted here.
Also, who said it was abandoned? Its marked as completed and from what I have heard there is an ending. How is that abandoned?