shafi
most of the indian school is having malayalees (so called your mallus) in management. most of the teachers in indian schools are mallus. but as i know none of these schools are malayalam medium, all are public schools following CBSE.
Shanti Nikethan also majority by malayalees. Check with the parents studying in these schools, do they face any problems bcoz of mallu teachers. Don't try to differentiate these institutions by states/languages/colors. All are Indian schools following CBSE, except MES is having CBSE and Kerala State Syllabus.
Bhaven's is a new school. The function he might have seen is specific malayalam language programme. I don't think these schools are conducting any common public programme in one regional language.