Frame challenge time.
No matter how bad things get, no matter how far outside of acceptable parameters things are, nobody but the single Troubleshooter wakes. There is no backup. No redundancy. This is, for some reason, intentional.
No way. This would make no sense at all to anyone.
Starliners are huge colony ships. They carry enough equipment, building materials, embryos, colonists and nutrient rich rations to permanently establish a sizeable colony on a far-flung world.
These exceptionally valuable resources (and lives) are not going to be risked on one person being successfully woken without problems and that person being able to fix the problem or make the required decisions.
No one, from the accountant responsible for the insurance policies, to the CEO responsible for their huge retirement package to be enjoyed without lawsuits for decades, would want to risk all of that on one person.
The backup crew would be a minimum of three people, with a well defined decision making process that the AI requires them to follow.
The backup crew would have a backup and the backup-backup would have a backup.
You're not risking all that investment on one guy who may wake up and e.g. go nuts or be brain-damaged or be blind from some weird side effect. You need numbers to reduce the odds of a problem and backups to make sure that doesn't happen.
However the ship designers know that there may be unforeseen emergencies.
But apparently can't do math.
Not only would the backup crews have multiple members all woken at the same time, you'd make sure they were distributed over different parts of the ship so that if some catastrophe has blown a huge chunk of the ship apart or irradiated it, that won't wipe out the whole backup crew unless something that would equate to destroying the ship does.
Each backup person (part of a backup crew) would have access to a full set of rescue resources so they can try, if all else fails, to operate alone.
But you don't plan on working alone. You never start out with a huge risk and hope it works out. Engineers don't do that. Ever.
The type of emergency requiring more than one person ?
There's damage to two systems and it requires that all-purpose fixing machine the human to fix both. Problem : they're both linked and work needs to be coordinated. Problem : the critical systems that need to be monitored are in a third location and the damaged AI can't help. Problem : You start fixing the problem and Bang ! One troubleshooter is dead. You still need both problems fixed together. You need a third grunt.
There's a useful model for this : planes. In an emergency generally training is for one pilot to fly the plane (if possible alone) and one to troubleshoot. You split the tasks because you can't rely on the automation in an emergency (sometimes you can, but you have to troubleshoot first before you can safely assume that).
There are other issues. One person thinks of one solution. But maybe the other two or three people think of a better one. Put another way : "Aliens !? But I'm an engineer and doctor not a diplomat and linguist !". You need a mix of skills and a mix of mindsets to arrive at good solutions to unforeseen problems.
What of backup person gets critically injured trying to fix something ? You really think you're not waking up the doctor ? Does that make any sense ?
Also note that these backup crews are not to be seen as a "just in case" - they're an essential system. They'll be highly trained (and well paid).
So I think it's not realistic that anyone would plan for just one backup person. Never.