What you are saying makes sense to me for the most part. However, regarding the last paragraph, the transceiver device I'm using is isolated and is referenced to the external galvanic level (ISO_GND). Since the TVS diode is hooked up to the chassis ground, which is at a different galvanic level, I still worry the diodes would conduct arbitrarily if these two galvanic levels diverge too much. Does it make sense?

It is established by the GND output of an isolated power supply (namely TDN1WISM)

@winny did already. I hope it helps explain.

If my reasoning is correct, the ground potential difference is unknown, as they are floating with respect to each other. Hence, they may or may not be separated by 60+ V. I believe I do fall under Class I btw

Exactly, the distortion is on the rising edge. I hadn't noticed the 3V Vth, thanks for that. I'll also try lowering R2 and get back with results. Thank you

I'll try with the s-d capacitor tomorrow at the lab, I'll let you know.

@KyranF haven't tried but it makes sense. I'll add that to the list.

You're right, I don't need it to be bidirectional. The reason I'm using that circuit is that it experimentally gave a better frequency response than simple inverter I tested.