How to do translation via csv file imported from PHP my admin
You can trnslate Po files with  POEDitor but if you insist use csv 
I suggest you use csv2po , export drupal translate in po file, convert po file to csv translate them in excel (or anywhere you want) then convert back it to po and import it to your site.

some quote from its documentation


  csv2po allows you to create CSV files from PO files. This allows you
  to send translation work to translators who do not or cannot use PO
  Editors but who can use a Spreadsheet.
  
  po2csv allows you to send CSV files, which can be edited in any
  spreadsheet, to a translator. This document outlines the process to
  follow from the raw po files -> CSV files -> back to PO. We also look
  at a case where you may have submitted a subset of the PO files for
  translation and you need to integrate these.