Chrome Version       : 52.0.2743.76
OS Version: 8350.56.0

What steps will reproduce the problem?
1. Enable Dvorak keyboard (chrome://settings/languages) and switch to it
2. Enable ChromeVox
3. Use hotkeys to adjust speech rate

What is the expected result?
Shift+Search+[ should decrease rate;
Shift+Search+] should increase rate

What happens instead of that?
Shift+Search+[ has the same effect as Shift+Search+- (decrease granularity)
Shift+Search+] has the same effect as Shift+Search+= (increase granularity)

Not much of a mystery: with a QWERTY physical keyboard, the - key outputs a [ in Dvorak, and the = key outputs a ] in Dvorak. So ChromeVox is using the QWERTY value of these keys (but *only* these keys) instead of their Dvorak values, which is weird when my system keyboard IME is Dvorak.