If those are the only tests she falsified, and did tests properly at higher temps, such as 25 degrees F, she's probably right and all is well.
Searching for the coldest temps, it looks like these isn't any water where a sub could go that's less than 28 degrees F.
Perhaps investigate why one would test at such low temps.
Perhaps our subs are capable of things you’re not thinking about.
Testing at conditions not normally perform at are to simulate use at normal conditions over an extended period of time often called “accelerated testing”.
Falsify test results and certificates occur more often than anyone wants to admit. Determination of whether to charge and go to trial is largely based on if the company has large financial resources for the government to gain from and if the project is to big to fail or not. Think of the Challenger; you heard about only after a public failure. The movie “the Challenger disaster” is a good movie.
Subs are not always submerged.
The temperatures of -100F are certainly possible to be experienced during operations in the Arctic and Antarctic.