We make it clear with companies we engage for support - ALL meetings with their staff must be with people that proficiently read, write and speak English.
I have ended probably 3-4 meetings over the years when we simply could not understand the staff member of the support organization. It’s unfortunate but time is money and the meeting was going poorly due to the underlying language challenges.
Agree that fluency in English is essential.
China, SK, & India have been my most frequented experiences aside from Western & Eastern Europe. For some reason, the Indian dialect of English is the most challenging.