You have created your own data source with key user or partner tools such as PDI.
You notice that the descriptions of key figures and characteristics do not change no matter in which language you log on to the system.
Texts for key user or partner data sources are stored in the object locally and will not be translated.
This works as intended.
You can use the design join or design union data source interface (Work Center Business Analytics, View Design Data Sources) in SAP Business ByDesign and change the text in the orange area on the left.
Please be aware that this changed text will not work like a translation. This way you will only be able to influence how descriptions are displayed in the data source / report.
KBA , AP-CI , Customer Invoice Processing , How To