Hi tve,
did you manage to make this work?
I think the problem is related to TPU accessing the base model that Model Makers uses on Colab.
Model Maker uses the base models from TensorFlow Hub
You can set an env variable to use the models directly on GCS and this might fix your issue:
import os
import tensorflow_hub as hub

os.environ["TFHUB_MODEL_LOAD_FORMAT"] = "UNCOMPRESSED"

did it help?