The thing with infosec is that no matter if you're a consultant pen tester or an in-house member of a blue team, a high proficiency in technical writing is required. And few certs demonstrate that the person is a good technical writer. It's not enough to know the answers to multiple choice questions. It's not even enough to know how to exploit things. If you don't understand something well and can discuss it in techn…
Knowing basic English is a prerequisite to any tech job. There's nothing else you need to know to explain a bug. And there's TOEFL/IELTS if you're looking for English language certificate.
Edit: And, in contrast, I've met people who I had a hard time communicating with in spoken English but, had no problems with once we did our communications in writing or with a written point of reference.