To use a client you need to export UAVCAN__CLN__.... This design where you need to specify the direction of the port explicitly is actually a deficient one. I am considering to discard it in favor of omnidirectional names when this change is implemented:
The scheme I am envisioning is a much simpler one: cyphal.sub.id.PORT_NAME for subjects (both subscriptions and publications), cyphal.rpc.id.PORT_NAME for RPC-services (both clients and servers). This will have certain positive implications on orchestration (where a multitude of topics needs to be configured at once in a config file) and for the eventual named topic support.