I just spoke with Microsoft, and for now, there is another temporary solution to not being able to use the Quick Assist app with a screen reader. They told me that, with Narrator, it is usable with the following instructions:
1. Quit whichever screen reader you have running, unless your screen reader is Narrator.
2. Start Narrator with CONTROL plus WIN Key plus ENTER, unless Narrator is already running.
3. Open Quick Assist with CONTROL plus Win Key plus Q
4. While holding down the Narrator Command Key (usually CAPSLOCK), press the Space Bar to start Scan Mode.
5. Press the letter E to navigate to the edit box where you would enter your code.
6. Press the Space Bar to enter forms mode.
7. Enter the code, and proceed as usual.