You can communicate with other people designing and using the standard via these means:
Use there links to discuss UK extensions to the standard, standard taxonomies we use in the UK and UK implementation issues
UK extension Slack workspace
Issues list in Github
Implementation of the standard is discussed in the LGA’s Local Services Open Data Project group and via OpenCommunity.
Use there links to discuss issues on the base Open Referral standard and everything that applies generally, rather than just in the UK
Schema specification (HSDS) issues in Github
API specification (HSDA) issues in Github