I'm still wondering what's the best way of doing the l10n part for this. Do you think the model of the portalboxes is any good? `Collection <- CollectionPortalBox (+ ln) -> PortalBox` where the language is put on the `n:n` relationship.

* https://github.com/jirikuncar/invenio/blob/pu/invenio/modules/search/models.py#L505-L511
* https://github.com/jirikuncar/invenio/blob/pu/invenio/modules/search/models.py#L527-L544