I don’t think much has changed but I’m still willing to help advise developers of KeePassRPC ports. Getting the Kee browser addon to talk to other KeePass ports is essentially still a case of the KeePass port to add support for the KeePassRPC protocol. That could be embedded into the port itself or via a plugin system.
I’ve recently released a Javascript port of KeePassRPC. It’s initial focus is upon working with Kee Vault but if other KeePass ports can incorporate npm modules, I’m happy to discuss any changes that would be needed to ensure it works more broadly across multiple KeePass ports.