<A HREF="https://de.wikipedia.org/wiki/Heyting-Algebra">Wikipedia</A> uses "Locale", capitalized as a German noun but otherwise unchanged. It seems to resonate with how the word was originally introduced by <A HREF="http://ojs.statsbiblioteket.dk/index.php/math/article/viewFile/11409/9426">John Isbell</A>:

> "an inspired choice, which conveyed all the right overtones about the
> spatial nature of these objects without causing their algebraic
> underpinnings to obtrude, and which at the same time was easily
> capable of all the necessary inflections".

    [Handbook of the History of General Topology, Volume 3]

I might add that "locale" is a Fremdwort in English as well: the Oxford Dictionary gives its origin als "late 18th century: from French local (noun), respelled to indicate stress on the final syllable".

Some places of usage:
<A HREF="http://www.dmg.tuwien.ac.at/fg1/seminar/20040402.html">locales</A> ---
<A HREF="http://www.iazd.uni-hannover.de/~pigors/punktfreie-topologie/">Lokale</A>