Siri for non-English languages would require a major overhaul because she’s is quite frankly useless for ”mixed language” prompts -Its like winning the lottery when you get her to open an app or song in Apple Music that has a title in English.
The vast majority of songs in the Music catalogue have English titles so it boggles my mind how Apple didn’t think to implement a “listen for English when the word ‘play’ or ‘music’ are used“ feature into non-English Siri.
Non-English Siri will recognize one or two English words for an English song title correctly but then matches the rest of the English title with non-English words in your language that vaguely match the English ones phonetically, most commonly writing complete gibberish that neither makes sense as a title or a phrase in English or your non-English langauge.
It's not quite that simple, even though I agree that she's mostly useless. The reason why it took nearly 2 years from the initial launch of the first ATV with Siri remote to Apple actually activating Siri on ATV in Sweden, was that they trained it to understand mixed English and Swedish in order to be able to open movies, shows, music and apps with English names and titles mixed with Swedish commands.
The first time I tried it, it was comically bad. She understood absolutely none of the English, she kept thinking everything I said was strictly Swedish and misheard me accordingly. Then I remembered struggling with Singstar - I'm a vocalist but it kept giving me terrible scores until I realized that it kept interpreting any kind of extra flair as being tone deaf (Celine Dion would get a big fat zero, Christina Aguilera probably a negative score). The max score was achieved by just hitting the notes with straight, dull and borderline robotic pitch, no tremolo or other bells and whistles. I.e. you had to sing poorly to get good scores.
Since I speak English with a general American accent and Siri's guesses seemed to get worse the better my enunciation was, I thought - hey, maybe it's that Singstar thing where you have to suck to make it work. So I tried talking with a super thick Swedish accent. Bingo. This is what they adapted mixed-language SWE/ENG Siri for. Just speak nearly unintelligible English like a 60+year old Swedish politician and Siri suddenly knows exactly what you mean by "Tom Cruise" or "The Avengers" thrown into otherwise Swedish sentences.
Of course it shouldn't have to work like that. Google Assistant handles mixed language with a 95+% success rate in my experience. Oddly I don't even have to use the option where you enable two languages. I have it set to just Swedish, but I can still say anything in English and it'll understand me just fine. I tried the same with Spanish, it worked too. "What time is it", "vad är klockan" and "que hora es", all three resulted in GA telling me the time in Swedish. No luck with French or German though.
Given the size of Apple's war chest, the shape of Siri next to Google Assistant is pretty pathetic. Kinda like Apple Maps vs Google Maps when Apple had just launched it and it was kind of a joke. It's a decent alternative now. I wish Siri had a similar trajectory, but instead she keeps getting dumber. Her latest glitch is that she can no longer start up an Apple Watch workout for me if the request goes via my iPhone. It worked for years, but lately when I ask her "Hey Siri, start outdoor walk", instead of hearing the 3+1 familiar beeps from my Apple Watch I get
"Sorry, I'm having problems with the connection. Check that your personal devices is on the same Wi-Fi network as this HomePod". Huh? "Wi-Fi"? We're outdoors on 5G. "This HomePod"? My iPhone is a HomePod? WTH does Wi-Fi or HomePods have to do with outdoor walks? Not a word of it applies to the situation at hand.