Despite I made living for years by localizing the US web apps products for Czech/international users, I am a total English maximalist in this.

Choosing to use local language is like imposing bilateral trade restrictions (quotas, tariffs, capital controls, ...). And the same complacent stagnation effect as trade restriction have on the economies, it will have on the "human thought capital", imo.

There's no second best in currencies, and there's no second best in languages.

You're always be a step behind the world knowledge, or the world will be a step behind understanding you. And this gap ever compounds, until at some point, it's clear to everyone.

Local languages are cool for preserving secrets and local cultures, but not the best positioned at the brink of accelerating society-wide changes.