I agree that most of what you mentioned have been widely covered in the francophone media in Quebec, ever since the announcement of REM in April 2016. And that the CDPQi doesn't have the most transparent governance structure in place compared to traditional municipal transit agencies like ARTM, STM, Metrolinx, etc. And that there may still be chronic corruption/irregularities in Montreal's municipal infrastructure procurement process.
On the other hand, one could argue that because of REM's unique funding and arms-length governance structure, it has managed to avoid the chronic delays, repeated studies, and over-engineering of transit systems seen in other transit projects in Ontario and Quebec (which I believe was the original intention why an agency like Metrolinx was created as well). Hence the reason why the Quebec government has already given CDQPi expanded mandate to start working on Phase 2 REM expansions in the Longueuil, Laval, and other suburban municipalities outside of Montreal (e.g.
Longueuil's tramway project now officially falls under CDQPi's jurisdiction, which will likely see it become a new branch of the existing REM system).
At the end of the day, I feel like what matters to vast majority of people (folks not following transit forums...) is the speed which new transit infrastructure gets built. And CDQPi has proven to be very adept at managing this aspect of their projects, making sure that their progress is highly visible to the general public.