>>/3520/
> green dragon crystal
I haven't used it for specific personal things like that, I assume it's tied to if you are able to solve the karmic circumstances caused by that decision in the past. I know it's possible to directly combat major timelines if you can present a better one. It won't erase the original progression of events, you and some others will recall them, but you can change it so that things actually turned out according to the new timeline. 

It's irrational sounding but it will work according to time travel logic:
First I did this, then I went back in time and changed it.

That will be the official story, which won't make sense to those who don't see or accept it, but just the same. You have the apply the MMO logic here though, anything you do gets reduced to "almost nothing" in reality. That great super weapon upgrade ended up giving +1% +7 every 6 seconds and not some miracle solution. Time is surprisingly resilient.