TechCommerceModifiers works, but it is not currently being USED. The only uses of this ability were deleted in rev773. If you add a TechCommerceModifiers to another building, it displays properly.
If you want to see what I am seeing, insert this snippet of code into the XML for any building. I picked the Fire Pit. This should give a building +15% gold and +15% food upon researching The Wheel.
Code:
<TechCommerceModifiers>
<TechCommerceModifier>
<PrereqTech>TECH_THE_WHEEL</PrereqTech>
<TechCommerce>
<iCommerce>15</iCommerce>
</TechCommerce>
</TechCommerceModifier>
</TechCommerceModifiers>
<TechYieldModifiers>
<TechYieldModifier>
<PrereqTech>TECH_THE_WHEEL</PrereqTech>
<TechYield>
<iYield>15</iYield>
</TechYield>
</TechYieldModifier>
</TechYieldModifiers>
Now when I load up the game, the Civilopedia entry for the Fire Pit, the mouseover text for The Wheel, and the tech splash screen for The Wheel all show the +15% gold but not the +15% food.
View attachment 471070View attachment 471071View attachment 471072View attachment 471073
But when I finish researching The Wheel, now the +15% food and +15% gold are both reflected in the mouseover text for the Fire Pit and the city's stats.
View attachment 471074 View attachment 471075
What should be happening is that both the +% food and the +% gold should be displayed everywhere that the +% gold is currently displayed.
Does that explain what I want to see better?