JJ likely rewrote everything rushed last minute under orders from Bob Iger/Kathleen Kennedy. When they fired Colin Trevorrow, it fell on JJ to pull together all his scribbled unused ideas from TFA. This is why ROS doesn’t really feel like a story and just a string of random ideas–that’s exactly what it was. It almost seems like JJ was told NOT to use anything from the Colin script.
But he actually did use a lot of stuff from the Trevorrow script. A nebula leading to a secret planet, Rey’s parents being killed by a Sith, Kylo sacrificing himself to heal Rey, and Lando showing up with a huge fleet to save the day were all ideas taken from Trevorrow. So that line of thinking is clearly incorrect.