Closing as non-reproducible as existing repeat questions can be edited via the Sent box. To enable editing of existing repeats which are opened via the Sent or Inbox the correct bind::esri:parameters must be set to allow querying and updating the existing records. The following parameter must be set: query allowUpdates=true. See Survey123 documentation for more information on repeat parameters. For Drafts and Outbox of unsent surveys the repeats can be edited as the records have not yet been sent to feature service and therefore existing records are not being edited, which means the allowUpdates parameter is not required.
対処法
Not from within the field app. The underlying feature service can be edited from a web map, web app or by making a local copy for editing and synchronizing the updates.