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How to submit a translation for a frappe base module?

While working on my tutorial custom app I have fixed some of the lines in .csv file for my mother language in frappe reports module. Is it possible to submit the .csv directy or do I have to use the translation portal anyway?

The preferred way is to use the translator

https://translate.erpnext.com/

If you PR directly the files, chances are high that this is be either not accepted ot overwritten by a later import from the translator.