And you are just talking round in circles. About 5% of your project is Arduino and the rest is App Inventor. If you can't get the phone to translate speech to text and send it to it's Bluetooth, you are dead in the water and the crocodiles are coming - MIT problem But you do need to first ensure Arduino can receive the message in the vague likelihood of the above being successful - Arduino problem. To do this, all you need to do is have Arduino echo a "hello" to a standard terminal on your phone, like that by Morisch.
Nano + HC-05 is used by a bazillion users and there is no need to change from what you've got.
You might find these basic notes useful. The first few pages may be all you need.