Initially reported on https://github.com/mautic/mautic/issues/2607
In the PR #1587 and file
Line 1218 in c44c1ab
it seems you can add relatives values.
Those relative values are given by transifex keys which means that the value is different depending on the language.
Moreover, those values have to be written manually in the date field where we “expect” to write in the date format.
Add the translated relatives values in the dropdown operator. Then no risk that the user has to manage himself the text and by consequence insert error + generate error if mautic is used in different languages.