

I’ve really enjoyed Busuu (created by Chegg, a US company) for learning eng—> spanish and eng —>german. Their free version has annoying ads but it does give you a chance to test the interface. The yearly subscription fee isn’t bad for the premium version that gets rid of ads. I’ve taken traditional classes and also used various apps like duolingo. Busuu strikes a happy medium between immersion and clear, digestible grammar explanation. I also like their review area (for vocab and grammar topics).
The platform doesn’t support Vietnamese yet but has chinese, japanese, and spanish of the ones you mentioned.
The boringest franchise