I've configured Freradius (2.1.7) to proxy certain realms to another box, and generally things are working as expected.

Running TCPDUMP, I see:

11:54:26.205736 IP (tos 0x0, ttl 64, id 19359, offset 0, flags [none], proto UDP (17), length 518) blah.blah.blah.foo.1814 > blah.blah.blah.bar.1813: RADIUS, length: 490
        Accounting Request (4), id: 0xa0, Authenticator: 01340e6ef70c9e34963da801985fba40
          Accounting Session ID Attribute (44), length: 10, Value: 0003AA7A
            0x0000: 3030 3033 4141 3741
          Tunnel Type Attribute (64), length: 6, Value: Tag[Unused]L2TP
            0x0000: 0000 0003
          Tunnel Medium Attribute (65), length: 6, Value: Tag[Unused]IPv4
            0x0000: 0000 0001
          Tunnel Server End Attribute (67), length: 14, Value: [|radius]
            0x0000: 3131 392e 3136 312e 3932 [|radius]
11:54:26.206751 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto UDP (17), length 52) blah.blah.blah.bar.1813 > blah.blah.blah.foo.1814: [udp sum ok] RADIUS, length: 24
        Accounting Response (5), id: 0xa0, Authenticator: 0087779312270cdff8c88a995db9c098
          Proxy State Attribute (33), length: 4, Value: 90
            0x0000: 3930

Accounting request proxied to foreign server, Accounting response received from foreign server.
Response packet was received, was not firewalled or otherwise blocked.

However, when I issue status requests to my freeradius server, it clearly claims there are zero proxy accounting responses.

        FreeRADIUS-Total-Proxy-Accounting-Requests = 2302
        FreeRADIUS-Total-Proxy-Accounting-Responses = 0

Regards,
Phil P