I didn't see any other answers here, so I am just applying my own naive detective work here. Based off what you describe, I found a list of publications that stem from a larger project that this one appears to be part of:
The reference you are looking for appears to be this one, which seems to match your description (the full article notes they looked at the Chisasibi as you mention):
2021. Brittain, Julie, & Yvan Rose. The development of preverbs in Northern East Cree: A longitudinal case study. First Language 41(4), 376-405. DOI: 10.1177/0142723720969257