Thanks Robin by the report. I am in my PhD finals now, soon I will return the development.
As far I debugged, it is related with the babel package that I am using now to provide the different currency symbols in the spreadsheet, for currency conversion possibility (and future GUI translation if some one want to).
Linux appear to have already defined some system LANGUAGE variable that is not in Windows. I don’t know if it a Python babel package issue or just some definition that I have to add in Windows though the setup.py.
Some user told me about this workaround:
https://github.com/xesscorp/KiCost/issues/339