I'm pretty sure Nuance also does the Comcast Xfinity voice remotes. They are actually really well done. And it's a humongous customer to have your claws in.
Obviously accents and irregularities are also areas I'm sure they are focusing on, but I imagine that optimizing for real time, mobile and low CPU power devices is a huge focus for them.
"Xfinity Home, dim the bathroom lights to 40%"
"Youtube Yuri Gagarin"
Are both things it knows how to execute.
However, after Siri was sold to Apple, I don't think that they retained the EduSpeak portion for speech-to-text. (I honestly don't know - but it seems to me it did not; I don't think Apple wanted to pay that license fee to SRI).
[0] https://cloudsolutions.comcast.com/apps/64168/office-365#!ov...
And 100% agreed, the voice is great on the Xfinity remote. Was very impressed.