OK, so it seems there is no need for me to post a new question regarding this, as I am pretty much on the same boat as you, and well you didn’t get much feedback to your post.
I just started to play with voice assistant today. Similar to you my HA configuration is in English (I see it in English), but my family (the rest of the users) use it in spanish. Pretty much all the names of my entities are in spanish (cosina, luz vale, sala, etc).
I’ve been using Alexa, and it works GREAT with both languages at the same time. I speak to it mostly in english, my family in spanish, and often I even through spanglish in there and it works just fine. “Alexa, turn off sala” turns off the living room lights as expected. One cool thing I noticed is that it also does the translations. If I say “Alexa turn off living room” even though I have no entities named living room, it does the translation to spanish and finds “sala”. It didn’t work for all entities, but for the basic ones like kitchen, living room, dining room, etc., it works.
With voice assistant, I got it working in english, but it is far from Alexa. I had to go in and set up aliases for my entities, since “Zorra, turn off sala” wouldn’t work. (Yes my wakeword is Zorra). So now most of my entities have an alias in english.
I like the idea of running everything local, but seems to be a bit far from being “stable”, especially in spanish. Find it odd that I can type in the assistant “apaga cueva” and it works, I can also say it via the HA app, and more often than not it works, however I can’t get “enciende cueva” or “encender cueva” to work both verbally or by typing it.
Seems will have to keep my Alexas for some more time
