when exporting an Jira Plans plan into CSV there is column "parent" which delivers the title of the parent issue (e.g. of the parent initiative of an epic etc.).
but without the parent key it is sometimes impossible to recreate the hierarchy based on the export since the parent issue key is missing and sometimes parent and child might have the same title.
to me this looks like a bug and could be fixed easily by either adding the parent issue key to the export or allowing more configuration possibilities to the user when exporting.