I can confirm both that the text domain is wc-aelia-eu-vat-assistant
and that the EU VAT Assistant passes all its strings, as well as its settings, to WPML. That has always been the case, since the first version.
The “EU VAT field label” is one of the plugin settings. That field is is passed to WPML using the wpml-config.xml file, as indicated in the official WPML documentation about admin texts and options: https://wpml.org/documentation/support/language-configuration-files/#admin-texts. If you go to WPML > String Translation, you should be able to find the text there. Example: https://prnt.sc/1rbcunk
Update
Another example, from a fresh sandbox: https://prnt.sc/1rbgmet. This also shows the new domain woocommerce-eu-vat-assistant
, which we will update in the next release.
I also think that, to translate the plugin’s internal text, you will have to enable option Use theme or plugin text domains when gettext calls do not use a string literal
, located at WPML > Theme and plugins localization
(see https://prnt.sc/1rbgw6w). This is because the plugin still uses constants for the text domain, and the scan tool won’t be able to detect the correct value.
To save time, you can do that when we release the version with the updated text domain, the coming week.