A similar error I've been getting that does cause the app to eventually crash:
2020-03-11 17:30:17.635383-0700 Cirkus[46226:2540216] [ViceroyTrace] [ERROR] AGPSessionSendTo:1324 AGPSessionSendTo:: NOT ENOUGH TRANSMISSON WINDOW BUFFERS AVAILABLE!
I have nothing to offer except to say I see this error all of the time as well even though my game app works fine.
I am assuming this is what is happening ....
Viceroy seems to be a network algorithm which is used by Game Center to send packets over the peer-to-peer network. This error comes out as part of the viceroyTrace logging so I am assuming there was an issue sending some packets to some players in your game (ie: packet loss perhaps???) . I am assuming you are using TCPIP as a delivery protocol so the packets are re-transmitted until they arrive at the destination successfully. So you might get the viceroyTrace error but eventually the required network packets are received by the intended player (as a result of re-transmitting) and your game goes on successfully.
Thank you for your response! I am glad to know it is not just me.