As I mentioned before, I did my A-Levels in KDU College, an institution that has attracted many foreign students interested in pursuing degrees in law, engineering, and other disciplines. My foreign classmates were mostly from the Maldives, India and Bangladesh, and most of them had no problem integrating with the locals.
At the same time, there were often a lot of students from other countries in other programs - guys from Botswana, Mauritius, places in the Middle East. One thing I observed is that most of the African students kept to themselves in their own cliques, while students from other places mixed with the locals freely.
To some extent this can be attributed to racial attitudes. People from the Indian subcontinent look like locals, and so we probably have an easier time relating to them than we might with someone from the Middle East or Africa. A lot of my friends, especially the girls, were frightened of or otherwise not interested in mixing with African students. So I can see where the Botswana government is coming from when they worry about their students having a hard time integrating into Malaysian society.
But I think the real and main problem is one which Malaysians who study abroad might have noticed themselves: we stick to groups we are familiar with, to people we feel an existing kinship with. In UK universities for example, you often find colonies and cliques of Malaysians and Singaporeans who don't really talk to people outside their group. The experience of being in a foreign country and mixing with different people is largely gone because we climb into our own shells.
The same, I think, has happened with students from Botswana. Because their government sends them over in such big groups, they clump and stick together in their own groups; they feel no need to approach locals and befriend them, and the locals feel intimidated at the thought of entering a large group of people they are completely unfamiliar with. Students who have come over because of their own private initiative, by themselves, don't seem to encounter such problems finding a group of Malaysians to hang out with.
Now, I cannot say for sure how justified the complaints of some foreign students like those from Botswana are. Maybe the true reason for their difficulties in adjusting is something besides their social isolation. Without an empirical study it is hard to say. But I can see why students from Botswana would complain about this, and if we want to address this, we must understand the social dynamics international students encounter. Cliquing is prevalent wherever international students are; it even exists to a large extent at Dartmouth in the US, where I am studying. But if we want internationals to make the most out of their studies and stay here, we must figure out a way to integrate them better into the mainstream of student life.