On a Sequence detail page (Info tab), all the sequence’s tasks are listed with their estimation, start date, due date and assignees, but there is no way to export them to CSV or import them back.

Today, CSV export/import of estimations and dates only exists on the task type page. That page covers one task type across all sequences. When we plan a single sequence, we have to open every task type page one by one, export, edit, and re-import each file.