Nope. Changing the past is one of the few things a Dragon Broke does not. All the accounts of conflict come from within a Dragon Broke because only during a Dragon Broke gods are the flow of events personally, so they can't affect events outside of that time period.
I'm not quite sure I understand that last sentence there, but what about the alteration of time which results in a new god having always been a god? Also, the timeline could possibly be changed proactively, rather than retroactively. When I said from "what existed before", I didn't mean what occured before, I meant the innevitable outcome of the current state of things, in the future. Think about the alternate timeline theory in which the Numidium is still laying seige to Summerset. That's the kind of altered timeline I was speaking of. To use a metaphor, imagine a train is running down the tracks. It slows and the track change switch is engaged. It now, has a new destination. The old track on which it was running still exists, and other trains may move down it, however, this train (and all the people aboard) are not going to see where the original track lead, so they do not even think about it. For them, it does not exist. They continue down their new track, to their new destination, completely oblivious of the change in course. Of course you wouldn't be aware of a dragon break altering the timeline from the inside looking out, and sadly all of our accounts of the dragon break are written from this perspective. I simply fail to see how a dragon break altering the present would not affect the past or future, even if the jills try their hardest to fix it. After all, wasn't the whole concept of a dragon break invented to explain away contradictions in the lore? If a dragon break didn't alter a timeline, for better or worse, there would be no contradictions, and therefore no need for a dragon break. That's how I look at it anyway.
ALSO: When the dragon break is over the "present" that existed during the break is now the "past" and the jills have to make it make sense in a linear fashion, so they alter what happened, don't they? Don't the jills "mend numiditions"?