Of @Nick_Boyts solution doesn’t work you may be out just about out of options here. Some background on why:
- Revit will only allow one posted command at a time, with the posted command not running until the transaction is over and the focus returns to the UI.
- Dynamo will not return focus to the UI until after it completes execution, no matter how many times you tell it to work.
Without knowing more about the intended commands I can’t think of another way to execute these in sequence.