The standard behavior so far for my maps in Japan or China was to use --latin1, and hope that all towns/cities/names if not name:en present - got transliterated decently into latin characters.
However if using Unicode this is of course not happening.

Could there be a command like {set name='${mkgmap:trans:name}' }
That way one could build a map that is usable for people who do understand the local script/language, and who don't by setting all names e.g.
name=('name:en|name:int|mkgmap:trans:name''(name in e.g. Japanese Script) '

Even better would of course be if there would be an additional function to check if "name" is already in two scripts - this is often the case for Japan or Thailand or Singapore... Dunno if that is easy to implement. I hope/guess the above mkgmap:trans:name would be easy, as the code exists if you use e.g. --latin1.

--  
keep on biking and discovering new trails

Felix
openmtbmap.org & www.velomap.org