What do you call a government official who cannot be fired?

Solution 1:

As is often the case with languages, some words are impossible to translate exactly into others, and there are also some words that describe specific phenomena for which there is no equivalent word in another language. To my knowledge, there isn't an English word that specifically describes a government official who cannot be fired. The closest word that comes to mind is indeed tenure, but that (as you correctly stated) is usually used in the field of academia.

In the example that you gave, you could try saying: "A permanent government official cannot be laid off." You could also describe the government official's position rather than the government official himself. For example, you could say that the official has a "life-long job" or is hired "for life", etc.

Solution 2:

While the OP suggested and discarded tenure, it may be employed in areas other than academics.

From Dictionary.com (definition 4):

status granted to an employee, usually after a probationary period, indicating that the position or employment is permanent.

An example specific to government employees enjoying a permanent position would be federal judges. Federal judges enjoy lifetime tenure.

From "He Won't Be Smiling: How Federal Judges Could Be Donald Trump's Worst Nightmare"

As Alexander Hamilton argued in Federalist 78, the Framers granted federal judges life tenure to protect them from undue political influence...

Even with tenure, a judge may be impeached for misconduct, such as taking bribes. I suspect that Austrian civil service law of 1979 (from which the term Pragmatisierung was derived) has a similar guard against gross misconduct.