I tried to stay close to the original texts mostly. However, I changed the style of the audit test texts a bit in German.
For example, Checking for hardened kernel parameters became Kernel parameters hardened. I chose this Boolean-style way to not make the sentences too complicated.

I don't think this is a good idea or necessary.
We shouldn't change the meaning of the sentence if possible. The sentences indicate that something is being checked, a process. Therefore we should also convey this in the German translation. The way you currently translated this changes the meaning drastically, it now describes the state of something, example:

Kernel-Parameter [sind] gehärtet (Zustand, kein Prozess)
(eng. kernel arguments [are] hardened)

While this can be understood with the indicator of PASSED, FAILED, etc being on the right hand side for each of those lines, it imo unnecessarily changes the meaning and can potentially lead to users interpreting those sentences "as-is" and think that the above example actually means "Das Ergebnis ist, dass die Kernel-Parameter gehärtet sind" (eng. the result is that the kernel arguments are hardened), overlooking the FAILED on the right.

I have made some suggestions, improvements and corrections below.
I also provided an, in my opinion, much better way to translate those "checking" sentences. Its still not an exact translation because I agree that one-to-one translating them would be overly complex:
Ensuring no sysctl overrides -> Stelle Sicher, dass es keine sysctl Überschreibungen gibt (example for what would be exact one-to-one translation)
But, it still conveys the process of "checking" something, which I think is important.

Two more nitpicks and one oversight I noticed in my second review.

Otherwise, I'm happy with all translations/changes and for my part would approve this PR.

Thank you very much for your work.