just chiming in with a "how we do it" comment that does not specifically answer your question but does touch a few points of it:
We have tied together our automation through Alexa.
My wife has a moderate accent and is the iPhone user in our house. Early on we too noticed the issue with Siri recognizing her commands.
At the time were were testing Siri (i think it was iphone 4) i had purchased my 1st Alexa Echo device.
We noticed it had no issue understanding her commands.
Fast forward to today:
Our properties are Alexa enabled.
When you 1st enter the house you will see an Alexa Show with a personalized welcome, instructions on accessing the custom Roku channel containing how-to/troubleshooting videos and a list of Alexa commands they can use.
Tied to our Alexa solutions:
- Light switches
- Lamps/Outlets
- Air conditioner
- TVs
- Smart Speaker / Amazons (free) Music service
- Door locks
- Window Shades
- Multiple Echo devices (can stream same source across all four)
- Short-cut command to send us a message through Alexa