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..