Contextual filter for an indirect taxonomy term?
To rephrase (to see if I understood correctly):
You have a content type pointing to term reference #1, that is pointing to term reference #2. You want to show the content that points to term #1, with the context being term #2.

In that case, you'd need to create a relationship (see Using Views Contextual Filter and Relationship to display reference on referenced node)

(The following explanation would work best with entity reference instead of term reference - I don't use that field type so I'm not sure the relationship exists with it)

But in short, you'd create a relationship to "referencing entity from field_term_reference" (the field on term #1 pointing to term #2). From there you could create the "referencing entity" relationship from the field on the content type pointing to term #1. The contextual filter would be to the term ID #2 using that relationship.