How to create a name-surname structure for taxonomy terms?
This definitely worked for me:

Inline Entity Form + Automatic Entity Label + Token.
I added an entity reference field to my content type, pointing to a Taxonomy Term entity and selected "Inline entity form - Single value" as the widget.
What works great is that every time you edit the term from the node edit form, the term's label changes automatigally.

Here are some snapshots.

Add/Edit Node:

  

Newly created term (vocabulary list):

  

Node view:

  

Hope it works for you too!