From a generic engineerengineering point of view following term, Betriebssicherheit might be best fitting for dependability:
dependability :: Betriebssicherheit
Thisdependability. This term is usually applied to a technical (mechanical) structure in German but could also be applied to software when viewed as a systemic whole.
However there is no good generic term in German language. Your givenThe definition you gave and also WikipediaWikipedia’s define dependabilitydependability as a mixture of several attributes whichthat are already very broad already for itson their own. In practicereality, software in general is seldom measured like this really. (Itit probably should.). I am afraid this is why there is no term yet. ForThus, for a final translation, the context is important then.
reliability :: Zuverlässigkeit
InBy contrast the reliability, reliability is a term which measures a software from an end user-user point of view which usually does not include service, support or durability over time. You would say a reliable software is not know for crashes and it works okokay. I would translate it with Zuverlässigkeit.
Statement: My answer is heavily opinion based-based on a long year-year experience in software business and engineering.