Hi Federico Happy new year!!!
Findspots was changed after Portugal's meeting with Rahel, David, Elena, Manuel, etc. You can read the thread here.
As you can see, the numisdata282 Findspot section was deprecated (I need to publish this...) to change the new TCHI (Tangible Cultural Heritage Immovable), and yes, it is a thesaurus in the same way than material, technique, etc. The primary distinction lies in its own definition. Unlike standard thesauruses, this section doesn't implement the same model. Consequently, you must manually define the hierarchy in this way:
1.- Set the tchi TLD as prefix tipos in your config.php file, in the same way that your are defined numisdata,
2.- Go to thesaurus -> hierarchy and create new one.

3.- Fill the fields in this way:

Note: Don't use the create tool as any other standard hierarchy, because the definition exists, if you press the button you will need to update the ontology, because this button create a standard definition making a virtual copy of the main section instead to use the original definition.
4-. Update your ontology, see if you have tchi into the tipos field, if not, review the point one ↑
5.- Log out and log in, assign permissions in profiles and done!, now you can use the findspot field and the thesaurus tree.
I hope is clear.
BEst