5.2.1.2.2 The English language shall be available, on
request from any aircraft station, at all stations on the ground
serving designated airports and routes used by international air
services.
Does this answer your question?
ICAO is really anotehr toothless Tiger
Was never really meant to be anything else - it is a UN body, and never intended to be a regulatory organisation. It produces Standards and Recommended Practices, but these are not binding on Member States. The only requirement is that you tell the rest of the world if you don't follow the SARPs