i find it odd that the main issue they found is language proficiency.

i don't think i know a country that offers university entrance exams or tests in a language other than their own. or at least doesn't require proof of proficiency.

For example in Czechia there are many diverse courses and whole programs/degrees in English with no requirement of the local language.

The majority of universities (public and private) offer them to foreign students - and for a very low fee ($2000/year or so).

There are plenty of universities in non-English-speaking countries around the world that offer degree programs taught mostly or entirely in English, where students still need to prove proficiency, but in English instead of in the local language.

And as the article points out, Japan does have different admission criteria for international students, it's just that foreign-born children don't usually qualify for "international" treatment if they graduate from a Japanese high school.