That definitely introduces biases into the research system. There's nothing inherently superior about publishing in one language or another. Almost all of our evaluation committees automatically give English publications higher prestige. That's how it is in Canada, and that's how it is in just about every country in the world.
In Canada, it's important to admit that this adds a particular dynamic to the country's linguistic balance. When Belgian scientists switch to English, that doesn't affect their language dynamic, because English isn't one of their national languages. In Canada, though, any switch to English automatically influences the country's linguistic balance.