Same problem here. Tested it with
  • Google Chrome - Version 29.0.1547.57 m
  • Mozilla Firefox - Version 23.0.1
  • Internet Explorer - Version 10.0.9200.16660 / Update Version: 10.0.8 (KB28627772)

Language set via Quick Language Chooser (down left on the Board) to German = Dev Tracker in french, set to French = Dev Tracker in german, Set to Japanese = works, set to english = works.

Language settings under settings don't work at all.

Hope it's enough informations.

Thanks in advance