I mean JJ was originally going to start TFA with a severed hand floating through space so anything’s possible. I guess they thought it would get people attention. [EDIT: Wrote this before I saw Ash’s comment!]
Speaking of the flashback, apparently they were training on the same planet the Resistance Base is at, Ajan Kloss. But I’m like, why couldn’t it have been Yavin IV? At least Luke and Leia have a connection to Yavin, plus it would be a nice homage to Luke’s academy in the EU being on Yavin IV. You could start the flashback with an establishing shot of Yavin IV, and then add a bit of red hue to the scene perhaps to suggest the “planet-light” of the red gas giant. I guess it doesn’t add anything besides slowing the film down a little by adding an extra shot. Honestly I wouldn’t mind if the whole flashback was just cut, or at the very least, the lines about Leia’s vision were cut or trimmed.
Back to the helmet stuff. What if you modified that scene to change Kylo’s motivation to touch the helmet? Maybe Kylo is wanting to see if what Palpatine told him was true, and we can get a different kind of “force-back”. Maybe instead of random events, we could get glimpses that hint at how Palpatine survived and how it connects to the helmet (through object possession perhaps). Maybe Kylo could get glimpses of the Dark Side’s past (Palpatine) and the Dark Side’s future (Rey), and the intensity of this vision recombined their force bond.
Maybe it is really visceral for Kylo not only because it is providing backstory, but because he’s reliving how Palpatine manipulated him from a young age through Vader and Snoke. And maybe these strong feelings of isolation and loneliness Ben felt at that somehow reforges that bond with Rey, since those shared feelings are what made Rey and Ben relate to each other. So as Ben experiences these past memories, Rey experiences her own.
So to summarize, maybe Ben isn’t trying to use Vader’s helmet to somehow reconnect with Rey, but instead, he is trying to confirm what Palpatine told him, and the flood of painful memories and revelations inadvertently reconnects him with Rey, since those feelings are something they both shared. So not only could it be a more sympathetic angle for Ben to see how he was manipulated, but it could also give more clues as to how Palpatine survived.