Hello All,
Regarding the new standards, the language of the station on the ground CAN be used but English must be readily available for pilots (at least level 4 proficiency) needing it.
I quote from Doc 9835, 2.5 Language To Be Used
2.5.1 In Annex 10, it is stipulated that radiotelephony communications shall be made available when pilots are unable to use the language of the station on the ground. The upgrading of provisions governing the use of language for radiotelephony communications from a Recommendation to a Standard emphasizes the important link between communications and safety...As an example, Spanish is spoken as the national language in States from Mexico, through Central America and throughout much of South America. For International flights in such States, Spanish or English can be used, but English must be made available. International pilots flying in this airspace may use either English or Spanish....
Point 2.4 also explains the requirements of the Use of Plain Language and how it shall be used. If anyone is interested I'll post that subpart as well.
Best to all,
PE