Genre taxonomy here will be reflective of the multi-source metadata aggregation that populates Roon, so it’s more reflective of distributor networks’ median genre taxonomy than a company stance on musicology.
If you’d like to customize the handling for Tango Argentino or any other genre, Roon’s genre treatment is fully flexible as @Suedkiez mentioned. On the Genre page, click the three dots to open the Genre Editor dialog window, and select your own Parent Genre