No, you cannot set those values as you don't have any account that can be used to do so. You can try to do it, but you would fail as you have to have valid credentials to access FIMService and update any values there. And if you don't have such credentials,
you'd be unable to update them.
You can use Sync engine if FIM MA service account still works as expected to fill those attributes - create direct import flow from AD and export to FIM (remember that your direct flow has to be precedent)
Or restore your copy of FIMService database that you did before making changes.