I have a few questions with convert sub task to issue
First of all, if the status of the source subtask exists in the target workflow, the step of defining the target status is skipped, whereas it is possible that it has to be changed.
Secondly, I don't understand how the fields to be configured are selected in the next step: they are neither all the fields nor all the mandatory fields in the target type nor anything I can think of.
Thirdly, as there is no constraint on the fields that are mandatory in the target, the resulting issue is likely to be badly initialized. Some mandatory fields may not be editable in the target status if they are hidden or read-only.
Finally, I support the request for adding a permission to run this function which is currently not considered by Atlassian, since, for the captioned reason it is best to restrict it to user with administration rights.