Translation for multiselect field not working

Not sure why this translation is not loading in the panel:

  label: Themes
  type: multiselect
  options: query
    fetch: site.find('projects').categories.toStructure
      en: "{{ }}"
      nl: "{{ structureItem.catnl }}"
      en: "{{ }}"
      nl: "{{ structureItem.catnl }}"

Languages are correctly added.

It gives the following error:

for context: I forgot to translate these, while the client already did the input in the panel. So in order to skip the extra labour of adding the tags to every project I’ve found this way of doing it much more efficient.

Just bumped into this topic:

So I’ll be looking into this. It seems to handle the same issue