From user 'mrem' on the forums:
1. I have set:
Tools | Options | Appearance | Language = English
Tools | Options | Advanced | checked "Automatically try to reconnect when disconnected from server (RDP & ICA only).
2. Connect to some Windows server.
3. From inside of Windows server use logout.
4. mRemoteNG re-logon window opens. Everything is fine, except in 1.74 RC3 (I haven't tested any earlier 1.74.x version) some German language appears. I don't have German settings anywhere in my system and also I have English setting in mRemoteNG. It looks like a bug. See attachment.