Waiting for author
Reported for: Gravity Forms Multilingual 1.6.3
Overview of the issue
Some strings such as Save or Continue Later are sanitized by Gravity Forms in a way that makes it not possible for WPML to translate them. This is because we use MO files and due to the sanitization, the string does not match.
Workaround
We are in contact with the author and we we will keep this erratum updated as soon as we have any news.
In the meantime, you can use the Disable auto-formatting option provided by Gravity Forms plugin and retranslate your form.