Hmm, it needs a 'replaceSection="1"' on maneuverPhrases and you'll have to override the whole list.
You can actually add that in the override .xml, e.g.:
<maneuverPhrases replaceSection="1">
<maneuver provider="Bear right" text="bear right" spoken="bear right" />
<maneuver provider="Turn right" text="migi" spoken="migi dozo" />
<maneuver provider="Hard right" text="make a hard right" spoken="make a hard right" />
<maneuver provider="U turn" text="U turn" spoken="make a U turn" />
<maneuver provider="Hard left" text="make a hard left" spoken="make a hard left" />
<maneuver provider="Turn left" text="turn left" spoken="turn left " />
<maneuver provider="Bear left" text="bear left" spoken="bear left" />
<maneuver provider="Keep left (unsupported)" text="keep left" spoken="keep left" />
<maneuver provider="unimpeded through" text="keep centered" spoken="keep centered" />
<maneuver provider="Straight ahead" text="straight ahead" spoken="straight ahead" />
<maneuver provider="Stop at" text="stop at" spoken="stop at" />
<maneuver provider="" text="" spoken="" />
</maneuverPhrases>
The only one I actually changed is "turn right" (to Tourist Japanese), but I have to supply the whole list. I did try it and it works.
Feel free to file the SR, I'm going to fix it in 9.4 right now.
