Hi Markus
Unfortunately I didn't find a solution. Based on my tests, the urgent change tasklist is unlocked automatically when an import action is triggered. Afterwards, it locks the tasklist again so that no manual actions can be triggered via tasklist.
If you want to import via tasklist, you can do so by executing the import task of the Maintenance tasklist associated. This would require the tasklist variant SAP0 (remain in buffer queue) to be used by your Maintenance project.
Regards
Luigi