You’re comparing programming languages with forum software.
Programming languages is different. Because their compiler/interpreter can only understand hardcoded lexical afaik. But in forum software, you can easily translate most of things as we can see in Discourse. So you cannot compare discourse with pl.
There is programming languages exist which not uses English for sure. Google it and you’ll find. English is not an universal language. Of course it is using too much. But I don’t want to dig out why all people use it because it’ll took lots of writing about politics and human manipulation.