Thank you for your interest in this issue.
As a part of Jira Service Management Data Center 4.21 we have released column configuration on the Help center’s request list view. This allows Jira admins to select the columns that they would like to appear in their customer's requests list. It also allows customers to configure and order the columns.
The available fields are type, reference, summary, status, service project, requester, created date, updated date, due date, assignee and priority.
Given that the improvements to the Help center's request list does not yet support sorting by column, we will keep this ticket open.
Please refer to our documentation to learn how to configure the requests list.
Jira Service Management, Data Center & Server