[NTG-context] (mkii) language-specific options for \placeregister[index] ?

Hi, the following (with mkii) is probably not the most pressuring topic to most of you ... apologies! Although I have set \mainlanguage[de] the register seems to be unaffected. All my cultural heritage (i.e. the Umaut) is ignored!!! o( The problem is the sorting – keywords containing umlauts seem to be sorted after "e": Bestimmung Bühler Bildung Are there language-specific arguments/options for \placeregister[index]? Thanks, Steffen