If you want to start Xastir using some other language, you do that with command-line switches when you start Xastir. Once you use one of these switches, that language option becomes "sticky", meaning you won't have to enter that command-line switch again unless you wish to change languages.

If you type "xastir -?", which is an invalid command-line option, you'll see this:

  xastir: invalid option -- h

  Xastir Command line Options
  -c /path/dir       Xastir config dir
  -f callsign        Track callsign
  -i                 Install private Colormap
  -geometry WxH+X+Y  Set Window Geometry
  -l Dutch           Set the language to Dutch
  -l English         Set the language to English
  -l French          Set the language to French
  -l German          Set the language to German
  -l Italian         Set the language to Italian
  -l Portuguese      Set the language to Portuguese
  -l Spanish         Set the language to Spanish
  -l ElmerFudd       Set the language to ElmerFudd
  -l MuppetsChef     Set the language to MuppetsChef
  -l OldeEnglish     Set the language to OldeEnglish
  -l PigLatin        Set the language to PigLatin
  -l PirateEnglish   Set the language to PirateEnglish
  -m                 Deselect Maps
  -p                 Disable popups
  -t                 Internal SIGSEGV handler enabled
  -v level           Set the debug level
  -V                 Print version number and exit