It really is a shame there's apparently no easy way to do this.
I'm trying to recreate some of my most-loved & much edited Atmosphere patches in Omnisphere and so far it's not easy. It's a help that the basic patches & their samples all all available, but after that the real work with tweaking starts.
The Amp envelope seems to respond completely differently. Attack has less resolution than in Atmosphere, AFAI can see. Some Atmos parameters (Amp Envelope sensitivity) I can't find in Omni, & others are displayed with different values ((Amp sustain is 0.00+1.00 instead of db). So far I can't get the nice "blooming" envelope I have programmed in Atmosphere- where the sound "surges" nicely but settles down quickly to a much lower sustain- in Omnisphere as good as I have it in Atmosphere :-(.
I'm staying on it, but it's uphill work!!
PS Eric has always warned that expecting 100% forward/backward compatibilty is unrealistic. Atmosphere came out in 2002, right? That's a lot of mileage from one -great- product!