How about: "...to improve academic overall performance" instead of "... in order to perform better in international rankings."

Diversity has proven benefits in many cases, I see it in my daily work. It is much more than just a number in a ranking.

> low-income regions (e.g. ex-Russian territory, Asia)

Asia? Low-income? These times are gone in many places. You need to update your knowledge. Diversity in your workplace could help :-)