In the current status quo your nightmare scenario (having to debug a codebase with comments in a diffeeent language) is precisely the everyday reality for non-English speaking devs. A Japanese dev could easily make the same comment as you, the difference being he actually has to deal with situation in question on a daily basis.

You could make the argument that English is the "lingua franca" but the phrase itself demonstrates just how ephemeral that is. I've lived in places before where a generation ago Russian was taught as a "lingua franca". Nowadays you would be hard-pressed to find anybody with a good understanding of Russian (good enough to understand technical documentation) there, even amongst ethnic Russians.