Ok, thanks to an idea from Chappy7, and much help from tailred's Woodcutter logging services, the new game-log-kingdom-visualizer-feature is done!
To use this new feature... type a game number, including a "#" at the start, like #21439056. Highlight the whole thing and hit the "Kingdom" button. It will replace the game number with the list of cards in the Kingdom. Upon posting, it will replace the [kingdom ] tag with the card images, just like before.
You can still use the Kingdom button and the [kingdom ] tag exactly like it used to work also. Just list out any number of card names, separated by commas, surrounded with the [kingdom ] tag, and it will post images for them when you post. The "Kingdom" button will only check the Woodcutter logs if the text starts with a "#".
Remember, your game log needs to be loaded into Woodcutter for this to work.