It's not possible to translate the string Display number in front end, below the list of attendees. This option should be possible to turn on/off as it is useless when there are less than e.g. 10 attendees listed.
The text "Display Num" actually is coming from Joomla pagination, not DT Register. However, if you want to add this line to the DT Reg language file it should overwrite that still:
DISPLAY NUM=Whatever
There IS a space between DISPLAY NUM. This would be added to:
Thanks a lot! But what about making this choosable in back end? This is a feature most of us don't use under normal circumstances I guess. Only useful if you have a long list of events, more than e.g. 20-30.