In the magnolia-form-module i did run into a i18n-Problem.
When you submit a mail and you have required fields which you did not fill out you get an error-Message, e.g.
<autor-defined error-message> Name: is required
'Name' is the field-name of the form-element
'is required' is the label "form.user.errorMessage.mandatory" from messages_en.properties-file

The Problem is that this message ('is required') which is displayed to the end-user is not translated to the languages (de, it, fr) we have on the website.
As a workaround I thought i could use our own messages-files by changing the attribute "i18nBasename" from the form-paragraph in the config.
But this does not work. The reason is that the message-file is hard-coded in info.magnolia.module.form.util.FormUtil.java to "info.magnolia.module.form.messages".
FormModel.addErrorMessage() uses FormUtil

Suggestion for improvement: The form-module code is changed so it is possible to use custom-defined-messages-files.