50 points sounds huge, but there actually is no meaningful difference between -6.4 and -62 in such an endgame.*
6.4 is more or less "Black has a queen for a bishop (but I haven't found a way to make progress yet)"
62 on the other hand is "I have found that way to a position that is 100% won (but I haven't found a forced mate yet)"
This sounds like a bug. Using Lichess's analysis engine, it takes Stockfish 14 less than ten seconds to find a mate in 11 moves. Both 1...Kg3 and 1...g1=Q lead to mate in 11.
So there should be no difference in which move you start with, even objectively (of course as a human I'd go 1...g1=Q without thinking).
Do you know instances of chess books explicitly rewritten years later by the same author, this time with computer-analysis aid? Preferably with the author telling the amount of errors found.
No. This doesn't happen. Why would it? There is nothing to be gained by this.
What does happen with a few old books with good reputations that were written using ...
Yes it's possible. Sort of. It's one way people have compared the top players throughout history. The basic idea is that you feed the engine the position and the moves played by the players, and see how probable it is for them to play the computer's best move.
I don't know any ready-to-use program for this kind of analysis, however.
Here is an attempt to justify "Draw". What should be the plans for White? Obviously wander with the king to...
Force entry to f6. This would win by zugzwang after some manouvering (play B to c7 and K to f7, the bB gets "scissored").
Force entry to c7. The d pawn queens (or the a).
Force entry to b8. The a pawn queens.
Unfortunately for ...
So perfect play is a tricky so allowed the engine to play it out.
A review of the position using StockFish 14 indicates that White is winning with a positional advantage of +-1.51. This was discovered at a depth of 40.
I ended up running this to a depth of 120 at which point the position was drawn. I went backwards to find the critical position ...
Note that Q1 can nowadays safely be answered by simply using an engine. My gut feeling that White stands bad (bad bishop, off Nh4, rest also stands around the botany and doesn't do anything, open king, no attack whatsover to compensate) was vindicated by Stockfish, but I didn't guess it was already that abysmal (-2.5, almost a piece in a materially equal ...