You realize most of your examples aren't about multiculturalism in general, but specifically about Islam?
They're also a neat illustration of selection bias. Places with conflict make the news. Multicultural nations whose only problems are due to racism by a handful of dickheads are many, but they don't make the headlines. Nobody's going to read an article about the absence of ethnic conflict in the 170+ nations not listed by Trausti. Indeed, he had to include nations that no longer exist to pad out his list.
This is the same logical error that leads to the inevitable question from idiots every time someone points out that nuclear power is the safest way to make electricity - "WhAt aBoUt ChErNoByL???".
Being talked about isn't the same thing as being significant, nor as being ubiquitous. It's almost always the opposite of being typical.
'Dog bites man' doesn't get into the papers, but that doesn't mean that 'man bites dog' is the more usual interaction.
Let’s understand this. According to the lefty worldview, the many conflicts in Africa are due to the colonial powers arbitrarily setting country borders. Which is probably right. Yet, if multiculturalism is so great, why were there any conflicts at all?