Panasonic PhotoMOS Relay with AC Load
it will experience AC voltages in the range of 120-347Vrms

If you are using this device to connect to regular AC mains power circuits then the upstream indirect-lightning protection circuits in most building will limit the peak voltage to around 1500 volts with respect to earth. If you are using this beyond the home or office then it could be over 2000 volts to earth and sometimes may even be as high as 6000 volts on unprotected circuits.
In any of the above scenarios, the device is going to fail miserably I suspect.

This circuit will be protected with bidirectional TVS diodes.

I'm wondering how this is going to work because you don't usually find TVS diodes rated greater than 500 volts and this is far too close to the peak of 490 volts implied by 347 volts RMS. Even if you were able to find a 550 volt rated TVS then, how will that TVS be protected against the peaks of around 1500 volts you will see in lightning protection zones 2 and 3? A TVS is really just a zener with the capability of taking a very short-in-time high current surge and, to get one to handle peak currents of a hundreds of amps (as implied by the surge protection used in LPZ 2/3) is going to be really difficult.
The easiest way to do this is choose a device that can survive in the appropriate LPZ: -

Picture from here