I am using a similar iOS shortcut to the post "Drafts Record of Completed Reminders".
- Asks you to specify certain date (defaluted to today, but you can change it)
- Exports title, memo and subtasks as plain text via iOS Sharing menu
- Can delete logged tasks
Tasks completed on 2019/02/17 * Test Task 1 Memo (1st line) Memo (2nd line) - Subtask1 - Subtask2 - Subtaks3 * Test Task 2 Memo (1st line) Memo (2nd line) - Subtask1 - Subtask2 - Subtaks3