Thanks to suggestions from Thúy Kim Lê Phạm, I've added two sections to the "Links" page of the COTSEAL website: Southeast Asian Language Learning Proficiency Guidelines, and Language-Based Southeast Asian Instructor Associations.
There's not much up there so far: only GUAVA (Vietnamese) for instructor associations, and Vietnamese, Filipino and Khmer (speaking draft only) for language learning frameworks/guidelines. So if you know of language learning proficiency guidelines online for any other Southeast Asian languages, or any other instructor associations with their own websites, please send the links to me!