To customize eCommerce Product Catalog translations, place your customized translation file in the wp-content/languages/plugins folder. Files there are not removed when the plugin updates. The file name must follow the pattern of the files in the plugin’s lang folder, for example ecommerce-product-catalog-de_DE.mo.
To change only a few headings or labels shown on catalog pages, you don’t need a translation file. You can change them in the Front-end Labels settings.
The easiest way to add custom translation file
The easiest way is to use the free Loco Translate plugin from the WordPress plugin directory.
After you install and activate it, go to Loco Translate > Plugins and click eCommerce Product Catalog.
Find your language and click Copy:
On the next screen, set the language and the location of your translation file. We recommend the Custom location (wp-content/languages/loco/plugins). Files there are kept when the plugin or the WordPress language packs update:
Click the Start Translating button.
Now you can translate each phrase and save the file. Your translations are kept when you update the plugin.