In Swedish that is almost exactly what they are called, bat translates to "fladdermus" which is "fladder" (flutter) and "mus" (mouse).

Same in German, die Fledermaus. In fact, in English, the word "flittermouse" also means bat [1], although that word is rarely used now.

[1] https://en.wiktionary.org/wiki/flittermouse