FindCreativeObjectsWithTag can only be used in creative_devices or by referencing one like MyDevice.FindCreativeObjectsWithTag()
Currently the most simple way seems to utilize weak_maps and get the session as the key to save a device from a creative_device to later reference in other pieces of code.
This was discused in this thread Verse: FindCreativeObjectsWithTag should be able to function within modules - #33 by Mineblo