It would be great if WHMCS would use or create a own translation services for language files which are included.
For example the german language file is poorly translated and there is a community but it need a platfrom to share it with all other customers. An other way would be that WHMCS itself keep the translations up to date.
Currently there are a few translations for example:
https://www.transifex.com/projects/p/whmcs-frontend-translation/But if the project creator isn't up to date or don't update the main file..
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With that, you can always take the current language file, and make the translations yourself and provide them to us for inclusion into the WHMCS core product.
You can inquire with us in the ticket at that time about a reward if the translations are accepted into the product.