in excel-addin/src/taskpane/taskpane.js [240:246]
function _merge_field_suggestions(fields_obj, num) {
// produce a specific number of field suggestions
const fields = fields_obj['fields'];
const extra = fields_obj['extra_fields'];
var merged_list = [...fields,...extra.filter(x => x[0].length > 2).map(x => x[0])];
return merged_list.slice(0, num);
}