Known issue

Problem:
The client is experiencing issues with partially untranslated WooCommerce emails in Spanish, despite having translations available in the String Translation. The client updated WPML and modified the TranslateWpmlString.php file, but the issue persisted.
Solution:
1. We recommended updating the WPML plugins and add-ons to the latest version, specifically to version 4.7.2, to benefit from the latest bug fixes and improvements. Instructions for updating can be found at http://wpml.org/faq/install-wpml/.
2. We suggested applying a workaround for a known issue related to WooCommerce order update emails containing mixed language texts, which can be found at https://wpml.org/errata/wc-order-update-emails-may-contain-mixed-language-texts/.
3. After applying the workaround, it is crucial to double-check that all strings are correctly translated in the String Translation.
4. If the issue persists, we advised creating a staging site and performing a step-by-step isolation test by deactivating and reactivating plugins and themes to identify the culprit.
5. As a last resort, downgrading the WPML plugins by manually uploading the plugin folders or restoring a backup with a previous version was suggested.

If this solution does not resolve your issue or seems outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If the problem persists, please open a new support ticket at WPML support forum.