Custom Forms linked to a Help Topic are not added to tickets created by email

By design, custom forms are never automatically added to tickets created via email. Fields cannot be completed over email, and required fields would block processing. The Filter Action 'Set Help Topic' applies the Help Topic's Ticket Details Form only -- not any custom forms. Agents must manually add custom forms via More > Manage Forms on the ticket. There is no workaround to auto-attach custom forms to email-generated tickets in the current codebase.