@blondegeek, we are currently working to make those tags searchable via the new API. For now, I would recommend pulling every provenance document and searching through tags and remarks locally.
from mp_api.client import MPRester
with MPRester("your_api_key") as mpr:
docs = mpr.provenance.search(fields=["tags", "remarks", "material_id"])
# Do stuff with docs...
– Jason