Seems like your tool would be able to do what KiCost is currently lacking… a simple way to get the manufacturer ID etc into KiCAD.
You might want to try to contact @devbisme and see if you two can go along and collaborate: Latest version of KiCost: Faster! Custom Pricing!
As for ideas for improvement… the important thing I’m interested in would be to make it work on local libraries too. Not just in eeschema, but also in the schematic library editor/browser.
If I am to put in this kind of data I would want to have it editable conveniently in the libraries, I wouldn’t want to fill these fields in via KiCAD means in the lib editor even as it’s just too much clicking and error prone.