There are a variety of companies that offer those. Given where you are you may want to try local companies, like https://en.tlm.nl/moto-guzzi-triumph/039410009000-klepdekselbeugel-vierkant
Sadly they are currently out of stock. Try googling guzzi head guard. This company makes their own versions, not as pretty but arguably more robust. https://guzzipower.com/store/Headguard.html
You still have one good one, I assume. Any decent machinist should be able to make you a matching pair using the good one as a template. My wife made hers. Of course, she had access to a CNC routing table.