I could rant for hours about the sacred cows of D&D deserving slaughter, but I'll refrain.
All this is to say, the Dolmenwood campaign book is great and I own it. It was originally a setting for Old-School Essentials published through a zine[1], and I think they could have stopped at just a campaign book, the one that the OP links to. I just don't think we need any more flavors of B/X!
[0] https://index.rpg.net/display-entry.phtml?mainid=14165
[1] https://necroticgnome.com/blogs/news/the-end-of-wormskin