I honestly don’t see why a solid priest couldn’t be identified and ordained as at least a simplex priest after 3-4 years. Perhaps at that point he offers Mass but doesn’t give sermons of hear Confessions ... until getting some more time studying moral and dogmatic theology. We are in an extreme emergency situation and don’t necessarily have the luxury to wait 6-7 years for each priest.
Except the priest could run off and become "independent", and plenty of Faithful would be ready-and-waiting to put him up and have a priest to say Mass. He'd then be "free" of any artificial restrictions. There is only one priestly ordination -- it's not like computer systems where you can be given different levels or fine-tuned access (like Permissions in Android apps)
A partly-formed priest -- who, let's face it, would have the same complete Holy Orders that any priest has -- would then have the temptation to be the boss, say Mass, meet people, be independent, enjoy your favorite weakness (socializing, travel, money, food, wine -- priests are only human!) those dusty books aren't going to look so attractive. Human nature will step in.
It's like a young man at High School graduation who decides to enter the workforce instead of going to college -- barring some dramatic life intervention, college ain't gonna happen. Especially if said young man goes off and gets married and starts having kids as well.