1.I have the solution for how to repair this file. You may open it within Notepdad ++ text editor and convert to ANSI encoding. Than save it. You will be able to see what lines are not translated properly in POEDIT and manually translate them with NotePad++ using another .po file as example for missing lines.
2.You may create another translation file which can be the more easy way. Please use default woocommerce.pot file from wp-content / plugins / WooCommerce / i18n / languages and save your translation to .po file which you should rename to WooCommerce-es_ES.po. POeditor will create also .mo file with same name (WooCommerce-es_ES.mo).
The final step is to upload both .po and .mo files to the wp-content / languages / plugins /.
With best regards
Brian Johnson