Interesting. Upon exporting a shop as a module and opening it up, I find I can unlock the building. I cannot click any fields to change the text/number, as you may have guessed. But I can drag a number from a number field onto another number field in the same shop and it will add the numbers. I cannot, however, drag a number from the chat window to one of the shop's number fields.
So looking at the way your extension exports a building, the <shop> section is not tagged as static="true" but something else is blocking data or events from going between the scope of the module and the campaign. Or some such; I'm tired.
Hope this helps at least a little to figure out how to make the shops and other things interactive from a module.

