My temporary fix:
Replaced file-gallery.js:1653 with:
// FIXED: issue where WPML editor is set to translation editor
var fg_icl_trans_id = '';
var fg_icl_trans_match = $(this).attr('href').match(/post=([\d]+)&/);
if (fg_icl_trans_match)
fg_icl_trans_id = Number(fg_icl_trans_match.pop());