She'll be back in Mexico for only a month before flying up to Canada separately from me. From what I'm hearing this could raise some red flags I assume. I also have no doubt that the USA has information on her, I'm going to assume for the sake of being thorough that they know to the letter her activities here.
I suppose that all we can do is keep our fingers crossed and form a contingency plan.
Note that she will be automatically banned from the US when she leaves for a period of three years (this assumes her overstay is less than a year). Makes sure she does not try to re-enter the US during this three year period. This applies even if she gets Canadian PR.