To resolve the first question raised in the issue, I would change
the text to add "or NAS"
" If there are any Proxy-State Attributes in a Disconnect-Request or
CoA-Request received from the server, the forwarding proxy or NAS
MUST include those Proxy-State Attributes in its response to the
server.
A forwarding proxy or NAS MUST NOT modify existing Proxy-State,
State, or Class Attributes present in the packet. The
forwarding proxy or NAS MUST treat any Proxy-State attributes
already in the packet as opaque data.