alt Hacker NewsElse can be found in English text prior to computer existence. Else can't be found in a German dictionary as a conjunction [1]. The first suggestion in Duden is the name for alder tree in lower German. Second suggestion is a firstname. If a word would come from German, it seems the first step would be to look up in a German dictionary.
While the look up for history of computer language is interesting, the conclusion is completely wrong.
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I don't think the article author is concluding what you think they are.
The HN title reads "literal translation," which I didn't take to mean "literally".
The linked article doesn't really have a title. The article author states [...] "I think a carefully-chosen German word was probably translated as an archaic English word and then never revisited. Unfortunately we do not have the original German text to consult."
The claim is that it is a literal translation, not that it is a loan word from German. Ie the Germans wrote their paper for this new control flow in German wenn/dann/sonst, then took their Langenscheidt and looked up "sonst".
https://www.duden.de/rechtschreibung/sonst
https://de.langenscheidt.com/deutsch-englisch/sonst