Anything special in regards to maintenance for this breaker... any test for operational use to check it operation?

I only know about SF6 circuit breakers in theory. The only thing I can say is that SF6 is an environmental hazard as it is a very potent greenhouse gas. I think checking for leakages is probably very important.
I guess the operation/function should be clear. My wild guess would be that you might need to know how long it takes to extinguish the arc(?) Obviously the timing is important. Not sure about the equipment used.

You need to check with the manufacturer of the unit for recommended and mandatory maintenance tasks.