the Communist Party of Swaziland called it out as a populist distraction ... while demanding real change

Completely understandable, of course the name of the country matters little compared to material conditions.

... and continued to use the colonial name ...

But why? Like yeah the above is true, but how does that mean it's bad to move to the native name instead of the colonizer name?

Side note: it should technically be "eSwatini", but annoyingly no one — not even the eSwatini government — uses that spelling.