What you *really* want are two, perhaps even three, wealth maps - similarly to how you can toggle overlays on the main map regarding the shields, fortresses, etc.
Under it all would be your 'base' wealth map, showing the hardcoded value for each province, irrespective of improvements / effects. This would be your bog-standard way of describing roughly where wealth can be expected to be found, and which provinces have the greatest wealth potential, long-term.
Then, you could toggle the effect of province improvements and technology (probably all in one toggle), which would give you an 'updated' map, describing where wealth is generally distributed at this time, giving you a medium-term prediction of wealth.
Finally, you could toggle provincial effects such as looted, prosperous, dysentery, etc. This would give you a perfect snapshot of the wealth of Europe at that exact moment in time, a good short-term prediction of immediate wealth.
Of course, I have only one thing to say about this idea - it starts with a C, ends in a 2, and may or may not have a K in the middle of it.