I was very anxious so I researched every detail I could and even though I probably didn't need to, got a lawyer as well just in case it was more complicated than I had thought. The lawyer agreed with everything I already knew which was that like your husband I had a somewhat serious juvenile history too, and the juvenile stuff shouldn't be considered. But my adult cases were a bit more complicated due to varying jurisdictions and outcomes so I went for expungements and sealing, some of which I did myself, in my former home state earlier this year and got those. From everything I know, although I'm not a qualified professional, I'd probably put money on your situation going well in the end.
The bigger differences are that my adult record was more extensive and would have been straight indictable in CA over a short period of time - well it looked worse than it was anyway - and I don't have any ties to Canada. But with expungement, as long as CA deems it equivalent to their Record Suspension, which varies a lot by which state laws are deemed equivalent, that also means that more than likely they would also not consider those crimes to have happened. For me, that was advantageous. And even though the lawyer said 3-4 months because according to her I have no criminal record, technically, due to the juvenile record not mattering and the expungement, she surmised that I wouldn't end up going through the whole process. However, if I do, and I believe your husband will end up doing as well, the general timelines given in this forum are a year or more. Hopefully they consider humanitarian reasons. I have seen people here noting that they had CRs in process that seemed to have stalled but once they submitted something else, like for work permits or PR or something, that suddenly the CR moved much quicker. If mine is only a few months it will be because I didn't have to go through the whole evaluation as my situation is a bit different on a legal level. That said, along with an explanation that none of the history matters, hoping they agree, we also submitted the redeeming evidence to show rehab too if they want to review everything anyway. For what it's worth, one of my most serious charges, that was thrown out at the time, had no real paperwork left after almost 30 years so I didn't even have proof that I was fully exonerated. I still got it sealed/expunged in that local court so at a minimum I have something that says it was 'closed' permanently. I'll definitely update this thread when I have anything I can share.