Hi David,
currently there are 3 possible ways to connect TigerGraph and Tableau: using JDBC driver (https://github.com/tigergraph/ecosys/tree/master/tools/etl/tg-jdbc-driver), using RESTAPI and JavaScript (basically Node.js). My colleague @Szilard_Barany is on it. There is also possibility is to use Python (TabPy + pyTigerGraph).
Best,
Bruno