The tag is present in Lintian version 2.109.6. That is the most recent version we know about.
A "Choices:" field is a comma separated list, and translated "Choices:" fields must have the exact same number of elements. One of the translations does not follow this rule, you should contact the translator and request for a new translation where elements of "Choices:" fields have no embedded commas.
Cdebconf understands escaped commas in such fields, but packages outside the scope of debian-installer must not have them until they are also supported by debconf.