Apparently there was a request to include it in the residential schools settlement (re abuse of First Nations children) but it was rejected:
http://www.residentialschoolsettlement.ca/SchoolDecisions.pdf"These requested institutions have been researched by Aboriginal Affairs and Northern Development Canada and assessed against the test in Article 12 of the Settlement Agreement for determining whether the institutions should be considered an Indian residential school."
institution: Convent of Jesus and Mary
province/lcocation: Saskatchewan Gravelburg
Canada's decision: Do Not Add To Settlement Agreement
reason for decision: Operated by Religious Organization
To be included in the settlement, "Canada must have been jointly or solely responsible for the operation of the residence and care of the children resident there."
In other words, there may have been abuse, but Canada wasn't responsible. However, this would have been in a period later than your grandmother's time there, I imagine.
I think that anyone who ever boarded at a school run by an RC religious order probably had tales of a difficult life, at the very least, to tell, if they wanted to talk about it, which many never did. If you could find material about other schools during about the same time, operated by the Sisters of Jesus and Mary in particular, you might be able to generalize somewhat from that. However, since they originated in France and were located in francophone communities in Canada, what materials there might be would likely be difficult to access because of the language barrier.
http://en.wikipedia.org/wiki/Religious_of_Jesus_and_Mary (not great English)
Religieuses de Jésus-Marie / RJM is what to look for. I'm googling around a bit and not finding much along the lines of what you're looking for ... obviously, most you find will be laudatory, as they are deeply embedded in French-Canadian culture and pride.