Last September my team and I debuted a system that allows our customers to get LE certs and have them installed automatically on their sites. Since then we have experienced 11,872 invalid anti-replay nonce errors. Our system is designed to retry the request when this error occurs. Simply retrying seems to “solve” the problem. And by solve I mean the order process continues without issues.
Boulder in that post refers to Let’s Encrypt’s API. It’s just the name of the API and most likely has nothing to do with your physical location.
The response in the thread you linked to that is likely related to what your experiencing is this one. Essentially, Boulder only allows X amount of nonces to be active at any time. Once X is reached then Boulder begins invalidating nonces starting with the oldest ones. This means that if you make a request a request to Boulder and then wait a bit it is possible the nonce you received previously will be invalid when you make the next request. I am unfamiliar with the service you’re using so I’m not sure how they handle this.