Trying to make sense of the vision again:
1- We see Luke with R2 in front of something burning, I think this could be some dead jedis bodies being cremated by Luke. Ben might have killed some, but not all, before leaving for the first Oder, if any at all...
2- Presumably the next scene is set after #1, we assume Kylo and his knights killed jedis here, but that's less than certain at this point, this is an assumption. What if those people were jedis who killed themselves? The last one remaining would have been young Rey and an adult (possibly her own father), and he tries to club her to death (Rey might even have resisted, killing her own mother first, who knows), but Kylo kills him before he can, saving Rey's life. This scene was really filmed like the guy was going to club Rey (vulnerable camera angle).
The whole balanced forced thing, it's possible they realized that it was wrong to raise new jedis, that it would trigger an awakening on the dark side, Luke went looking for answers, but in his absence the new jedi order basically all committed a Jonestown-like suicide. Rey was supposed to be killed, but Kylo and his knights saved her. For whatever reason she is dumped on Jakku later on.
Still prefer the idea that Rey killed her own family/the other jedis and trauma caused her to forget everything, so Kylo and co. saw no use in her for now and just dumped her on Jakku. But the above could be another possibility.
Interesting. I believe Luke touching R2-D2 is supposed to be a sign of him giving R2-D2 the map to his location and R2-D2 was shut down the entire time compiling the map all by himself and finally woke up when it was done.