eck ignores delta

It's about order in non-eck fields delta referencing eck entities.
Eck sorts Drag-and-Drop order by eck instances ids – why?
In ordinary bundle of node material, in it's node
I've made delta (multiple values) field with machine name field_element.
that references to eck entity.
I use IEF → to create new "values" for this field.
That's nice: i can drag instances (title + image) in the field up and down to change their order.
But how can i output this order in a views?
Views displays this field values according to eck entity instances ids.
But i need according to node__field_element.field_element_target_id column order.
I've tried add
node__field_element.field_element_target_id AS row_weight
and order by LENGTH(row_weight)
in hook_views_query_alter:
$query->addOrderBy('LENGTH(row_weight)');,
but views query doesn't support functions in 'order by'.

My views displays eck ecntities,
i've tried add relation to node bundle containing the eck reference field,
but i can't add delta of the field – there is no such field.