Do you allow your users to select the interface language in their preferences? Then, customizing text in only one language will result in users with a different interface language missing the information you added. An example of that is the about page here on Meta, where only users who see Meta in English see the email address to message moderators.
The message you create with the automations plugin will be sent as you write it. It’s the same for all users, no matter what language they prefer.
I can’t say how relevant this is for your community, but perhaps you could disable the language selection for users before inviting them to the forum.