onion_skin_client_handshake is defined in
src/or/onion.c and performs the final step of the handshake when creating a circuit. This warning tells you that the handshake has failed.
The log message
circuit_finish_handshake comes from
command_process_created_cell(). This function tries to find out if the Tor client was the initiator of a circuit. If yes, the key processing is finished and the circuit will be extended. In the case of the error message the finishing of the handshake failed and Tor will close the current circuit.
In the last case Tor receives a relay cell and decides what to do with it. When this error message appears Tor wants to send it to the origin, but failed. (see
circuit_receive_relay_cell). If I understand the source code correctly, the relay cell is later dropped.
If I understand it correctly Tor saw a more or less incorrect cell (think of a package) and handled it somehow. The message shows you that something happened and Tor cared about it.