Fair enough. And congrats on teaching your kid to speak multiple languages. That is a wonderful skill that will serve her well. But this is like for a 1–3 year

Fair enough. And congrats on teaching your kid to speak multiple languages. That is a wonderful skill that will serve her well. But this is like for a 1–3 year old, maybe 5 or 6 at the outside. After the kids are reasonably fluent in at least their native language, I can’t imagine throwing occasional foreign words is going to give them unreasonable difficulty. I was thrown by the word “children” in the top-level comment. > seems to require clearly distinct user groups I’d be interested to see the research on this. I am skeptical that this is required. Side note: pretty well every language learner goes through a phase where they quickly jump from very limited ability to produce speech to impressive levels of fluency, in a relatively short stretch of time (weeks to months). Those leaps of improvement are not necessarily related to any specific external stimulus.