1) is there really a so-called "glass screen wall" facing those banana species? i am however quite optimistic about their language capacity in breaking through this invisible barrier. I am never inclined to question the viability of these new species, the 30% is a small world, and they can afford to visit it with no difficulty.
2) On the other hand, modern technology has made this multi-cultutral world much easier to understand. if you like, anything can be made clear and available in a few seconds using powerful tools like google etc. Seems i am more optimistic about this wonderful age, everything has been made as transparent as a crystal, on its origin, context, and connections with others, either in the 70% or in the 30% world.
3) Teaching may be an efficient means for spreading knowledge, but has never appeared to be the best pathway for acquiring a language. I find it is hard to convince myself there is a need to have a concern like this:), but it is constructive to get this addressed in a way like yours.
4) Anyway, it is good to share thoughts and valuable solutions to the raised concerns.