Waiting for PBI desktop « working on it »
When you know the host and port of SSAS Tabular instance, you just need to connect to it – and your entire PBI model (i.e. tables, relationships, measures, load scripts) becomes available for scripting via .NET API and Microsoft.AnalysisServices.Tabular namespace. When a model change is made and saved, PBI desktop updates the view automatically. You do still have to wait for this update, but only once per a set of changes – not after each model change.
There are tools
Yes, there are tools to work with the Tabular model. I prefer