Two observations from my experience:
1) While working briefly in Tehran, I was tasked with communicating some software design to some Iranian programmers.
They were moderately competent programmers but their English language ability was rudimentary, but their English vocabulary was slightly better than rudimentary. Since I do not speak a single word of Farsi. Communication was obviously difficult.
That was until I realized that it was mostly the English grammar and sentence construction that was the problem.
So whilst I necessarily continued using English words, it was fairly easy to re-arrange my sentences to make it easier for them to understand.
After 4 weeks I was joined by a colleague from the UK who observed that I was talking, in English, but very strangely.
2) I now work in an environment where I routinely see email exchanges between people from widely separated regions of the world who are all using "English" as the lingua-franca (oh, the irony of that phrase) to support various software systems.
It is fascinating to observe the muddle that ensues when the wrong words, diverse sentence construction and even mis-punctuation occurs.
It is often my role to step in and resolve the muddle.
And believe me, sometimes, it is just plain clearer to start a whole new paragraph with a conjunction :-)
<Rant>
Also don't get me started on any of:
1) "Your" and "You're"
2) "There", "Their", "They're"
3) "Less" and "Fewer"
4) Horrible neologisms like "Chill [Out]" + "Relax" => "Chillax"
5) brackets and the correct nesting thereof.
</Rant>
--
Ian W.