Am 19.12.2013 um 19:09 schrieb Hans Hagen <pragma@wxs.nl>:

Sorry for the confusion - hyphenation indeed works correctly (I
confirmed it earlier), but I was just noticing that the logfile still
mentions "language 'en' is active" which is harmless I guess.

normally you set the mainlanguage before \starttext

Even then the message reports english because it is produced by the \initializemainlanguage (lang-ini.mkiv) command

\unexpanded\def\initializemainlanguage
  {\mainlanguage[\currentlanguage]%
   \showmessage\m!languages9\currentlanguage}

which is stored in the \everyjob (core-def.mkiv) register. A better place for the message would be in the definition of the \mainlanguage command.

Wolfgang