You can use the following formulas in the Calculated Fields to export the total returned quantity based on different return status:

Lineitem Returned Quantity (All Status)

get_total(to_list({{ line_items.returns.quantity }}))

Lineitem Returned Quantity (Open/In Progress)

get_total([i.quantity for i in load_json_data({{ line_items.returns }}) if i.status == "OPEN"])

Lineitem Returned Quantity (Closed)

get_total([i.quantity for i in load_json_data({{ line_items.returns }}) if i.status == "CLOSED"])

Lineitem Returned Quantity (Canceled)

get_total([i.quantity for i in load_json_data({{ line_items.returns }}) if i.status == "CANCELED"])

Lineitem Returned Quantity (Requested)

get_total([i.quantity for i in load_json_data({{ line_items.returns }}) if i.status == "REQUESTED"])

Lineitem Returned Quantity (Declined)

get_total([i.quantity for i in load_json_data({{ line_items.returns }}) if i.status == "DECLINED"])