Manitoba's immersion situation is currently different from that of Ontario. In most cases, immersion is a creature of the school divisions. Consequently, what is called immersion in one school division may correspond to a 50% program starting in grade 4. The skills that students acquire will be related to the intensity and quantity of French and to the number of years spent learning it.
In some cases at the secondary level, it is enough for students to take 30% of their courses in French for the program to be called an immersion program. However, in a semester system, that may mean not taking a French course for a year. Is that really immersion?
With regard to management of the types of programs, the federal government could, for example, encourage the provinces to find a common definition of what constitutes an immersion program rather than leave it to each of them to do what it wishes.
They do a lot very early on and afterwards no longer know what they are doing. It would be a good idea to have rules establishing the number of hours of contact in French immersion, from start to finish, so that that is clear and everyone does virtually the same thing instead of having this umbrella called immersion that is very different from one place to another.
Manitoba did that, and I believe it has been very beneficial for immersion students in that province. It established an immersion curriculum policy defining how immersion is done back home in Manitoba.
I think that would be part of the solution.
The other is also related to the idea you raised in your question concerning the different skills of immersion graduates. We should have a national tool to determine the level of French language proficiency of all Canadians, regardless of where they graduate, whether it be from immersion, core French courses or university. A tool for determining proficiency levels would go far. Immersion parents would be delighted to have that kind of tool emerge and be developed in Canada.
We currently use the DELF. It works and is beginning to spread across Canada. However, I think we should have a Canadian tool one day.