The short answer is: no.
The long answer is: the author of m0n0wall has decided that translations add an extreme amount of overhead, since each time a new feature is developed (or an existing feature is modified), all the translators need to be contacted to get the proper translations for the new strings. Experience shows that people are often eager to start something new, but lose interest and give up or go away after a while, so it'd be hard to keep all the different languages synchronized. Failure to do so would lead to incomplete or mixed (with English) translations - something which immediately creates a very bad impression in most users. Furthermore, translating the interface of a firewall isn't as easy as it seems - the translator needs to fully understand all the concepts that are involved in order to produce accurate translations.
Side note: the native language of the author of m0n0wall is not English either. However, he believes that anyone who's trying to accomplish anything non-trivial with a firewall, especially an open source one, will never get around learning English anyway.
That said, everybody's free to start their own (translated) m0n0wall branch - the BSD license, under which m0n0wall is placed, essentially permits anyone to do anything with m0n0wall as long as the original copyright notice and license are preserved somewhere (see the license for details). It should be made clear that it's not an "official" version though.