1. add a link field to a term, with unlimited values
  2. enable translation of this field (with entity_translation)
  3. create a term and add some links: the button "Add another item" works like a charm
  4. translate this term and try to add more than one link: the button "Add another item" does not work

The ajax loading icon appears for a second, but after that there is no additional link field inserted.

See also another issue with entity_translation: #1744962: "Link title" field is disabled, but it shows at entity translation (maybe they belong to their issue queue?)