Taxonomy view page for double nested terms
Show only grandchild nodes on Taxonomy term pages

In more words: Add nodes to Taxonomy term pages that are tagged with terms that reference the term shown on that page. This means that nodes that directly reference the TID will not be shown. Instead, we show nodes that have an additional Taxonomy link in between, a sort of grandchild connection. 

We first introduce the "parent" connection (in your case it's "Architecture" from field_key_data). Then through it we bring in grandparent "Style" information from field_style. Since we want to show nodes that relate to that TID through that "lineage" we simply use Term ID Contextual filter with the "grandparent" Relationship.   


Clone (Duplicate) the default Taxonomy term View (which is of Content type). It already has one Contextual filter (Has Taxonomy Term ID) that is responsible for showing all nodes tagged with that term. Remove it, we don't want parents, we're only interested in grandparent. 
Add a Relationship Taxonomy term referenced from field_key_data. 
Add another Relationship Taxonomy term referenced from field_style, it will use the first Relationship. 
Add a new Contextual Filter Term ID, make it use the second Relationship, and configure it:
When the filter value is NOT available
Provide default value
Taxonomy term ID from URL
Load default filter from term page
When the filter value IS available or a default is provided
Specify validation criteria
Taxonomy term ID
Style (or whatever in your case)  
Under Query settings choose Distinct because you'll see duplicated results because Relationships introduce many connections so to prevent it Distinct only shows each node once. 


No need for Contextual OR BTW, we only have one Contextual filter anyway :) 

BTW you can "require" both Relationships since this entire scheme relies on existence of grandchildren.