I would talk to other parents who's kids are at that school.
Then, it also helps if the language is also spoken at home.
In certain parts of Europe, where most people are multi-lingual... the kids are now taught foreign languages in primary school. Not just from middle school and onward.
I would also, check out the school's curriculum and what their results are per education standards/learning per grade. And if the kids, are on par, academically, not only per language acquisition.
My kids are bi-lingual, since my Husband is European, and they were born into having languages at home. They also learn other foreign languages at school. Hawaiian, Japanese, Mandarin.
But they are taught in English.
But, it also helps if the parents also speak the languages.