When at-spi sends a text-changed signal, it calls atk_text_get_text to retrieve the text that is being inserted or deleted.  Orca uses this information to, for instance, read the character being backspaced over if backspace is pressed.  So, ideally, a text-changed::delete should be fired just before the text is actually removed, so that atk_text_get_text will still return the text that is about to be deleted.

Repro:
1. Run Orca.
2. Run Notepad.jar.
3. In the Text window, press a key, then press backspace.

Actual result:
When backspace is pressed, Orca will say nothing if the last character in the document is removed; otherwise it will speak the character that is now under the cursor.

Expected result:
Orca would speak the character that was just deleted.

You can also test by monitoring text-changed events in Accerciser and looking at the detail.