First of all, as you said, don't give a game state at all if it's wrong.
The reason it matters is that it gives wrong information. Everybody counts the value of Victory cards during the game, maybe not every game or all the time, but it matters often enough that you do, and should. With your overly complicated reasoning, you actually try to make the point that we can't do that, because there isn't a "necessarily correct answer" to how many points the cards are worth. A Vineyard is worth [Action cards] divided by 3, it's that simple. If you lose an Action card later, or get one, maybe it will be worth more or less, but there certainly is an answer to what it's worth at any given point. Even the VP counter acknowledges that. If you "never get any VP" until the end of the game, how the hell can there be a VP counter?
If the game abruptly ends and you're given the wrong information about what the cards were worth at that point, how is that not a problem? Either you'll think you were wrong in your count, or you'll have to check for yourself. You might think you could have ended it before, or misplayed in some other way. If you are just happy with your win (or okay with your loss) and want to move to the next game immediately, then fine. But the log is there for people who want to check out the game and maybe learn from it. It shouldn't give wrong information, not about which cards were in the players decks, and certainly not about the current VP counts. Jeez.