I've been thinking about this more. I like Baker as-is because it's a setup rule; you don't have to remember that Baker is in the game while playing. For stuff like Golden Age, Discovery, Taxes, and City States, I think it would be better to have a separate Decree card. Especially because you can e.g. put the Taxes card sideways under the affected pile as a reminder, and likewise with Golden Age. The other three (Royal Pardon, Landholders, and Latifundium) could be on Kingdom cards, but probably would work better as Decrees.
OK, with that out of the way, I'll critique the suggested Decrees.
Royal Pardon - At the end of the game, each Curse is worth 1VP more. (turning them into confusions)
This doesn't seem terribly interesting to me. What about, "Curses are Action cards with the ability, 'Return this to the Supply'?"
Landholders - At the end of the game, each Victory card is worth 1VP more.
Hmm, makes Victory cards better. That might be fun, especially with Victory enablers like Crossroads. I think it helps smaller VP cards more than bigger ones, so it seems a bit redundant with Latifundium. Probably you just want whichever one ends up being more fun. It's possible that neither changes the game enough to be interesting.
Golden Age - Gold costs 1$ less, but not less than 0$.
Not a big fan. You could maybe have a Decree that made Treasures more expensive, but I'm leery there too.
Discovery - At the end of their Cleanup phase, that player draws 1 card.
OK, I like this one. Not much else to say. Definitely worth a shot.
Taxes - The next kingdom card selected costs 1$ more.
Probably this just means nobody buys that card. Try "The next Kingdom cards selected costs $1 less." Then you've got a game-changer.
Latifundium - Provinces are worth 1VP less.
See Landholders.
City States - Each player starts their turns with +1 buy.
Not super-exciting, but I think worth trying. Maybe you could combine it with something else to jazz it up a bit. "At the start of each turn, choose one: +1 Action; or +1 Buy."