I'm also having issues to understand what Juniper means by "reverse static NAT".
I think that reverse static NAT is the extension of the fact that Static NAT is planned to Work for traffic from A towards B, but also when communication is initiated com B towards A (reverse static NAT)
I guess this doesn't apply to the traffic from B towards A when the session is already established by A, (even if technically this would be DNAT), as in this case Juniper says this traffic is "fast path" processed, and so no NAT type is mentioned.