For nearly 3 years, my husband was assigned to a remote island as a military liaison officer to a foreign Navy with whom our country is allied. Our children attended a private school on the island. The students were mostly Tamil, Hindu, Roman Catholic, Buddhist, and, well, too many others to name.
We quickly recognized that the Tamil children were incredibly well-disciplined, well behaved, and extremely polite. My son's best friend was Tamil and we had to quickly adjust to the social customs that were expected of us when his friend would come over to our house after school, for homework, and then relaxing at the beach. When in the US, when one of our kids went to a friend's house after school, I'd just swing by and pick them up. But when it was time for our Tamil guest to go home, his entire family (parents, siblings) came to our house. They all stood at the door while I called for our guest to tell him his parents were here. But they didn't leave. I somehow got the idea that I was to invite them in, which they graciously accepted. I invited them to sit down, and they expressed such gratitude for welcoming their son into our home. All I had done was let him come over for a couple hours to work on a school project with my son! Thankfully there was sparkling water in my fridge, and some fruit which I transformed into a pitcher of water with lemons in it, and a fruit plate, faster than I have ever thrown something together before. Then my son was invited to their home a week later. They said they'd look forward to me and my husband and our daughter coming to get him at 5 pm so my husband left work early, and we all dressed nicely and were received in the most pleasant manner possible as we collected our son, treated to tea and some kind of cookies or biscuits. They remain good friends of ours even though we are on opposite sides of the planet now.
But the children's discipline did not come from the school, it came from the families and from the home, and the children had great respect for their own families, their own religion, and for society in general. They showed great respect to our family, even though we were so different from the friends they had known before arriving on this island (we're northern European/Scandinavian descent, pale and white skin with blond or red hair, and to be honest I had never even heard the word Tamil before). My children were welcome in their home and they graciously taught our children how to act respectfully (when to sit quietly, and what their prayers and words would mean, and why they were doing certain things like lighting a candle or reciting something) during their religious observances, while all the while respecting that our children were Protestant.
I think that discipline comes from the home. The school is there to teach reading, math, and to enrich the child's mind and expose the child to all the wonders of learning.
If you maintain a respectful, considerate, kind family atmosphere at home, while making sure your daughter is following your Tamil traditions, and helping her to learn respect for children who are not Malaysian or Indian or Tamil, then your daughter will most likely learn well in an English speaking school. Our Tamil friends spoke Tamil at home, but they recognized that their children would probably travel and would need to know English. They also learned Dutch and Spanish.