I think I misunderstood something of the transformation of the body as spoken of in Falun Dafa. It was my impression that it was a step by step process where the surface 3D body was to be cleansed first, gradually from qi to milk white state to gong, at which point you're done with it and move on to do the deeper layers. There was talk of how past buddha cultivators would fail the transformation of the very surface, forcing them to leave an "anchor" which would be something like a large boulder or mountain top. If the physical object was destroyed or withered away with time, they would die. Some buddha huh?

So the unique selling point of Falun Gong was that you'd be able to transform this anchor and take it with you.

Over time as I started recalling my past lives and looking at what I did, it seems I performed this every time, one body state like this existing for every life. So it's not just a "once ever" thing as implied. The difference was the method being in sync with the culture of the time, so with no complex science the understanding would use different concepts for the process. In London the logic was as simple as
>meat can be preserved in alcohol, so if I drink wine and kill myself I'll be immortal

No one today would be able to believe this, but the process isn't based on having a very detailed understanding of why it works, faith is the deciding factor. Same way as the story of Frankenstein by Mary Shelley was scientifically believable at the time, it was possible to fully believe in the quoted logic.