Remember how the original primes communicated with Sam in english, although they were dead a LONG time ago (and even the fallen-one and the ancient decepticon-turned-autobot) who all predate WWW etc.
All I want to say is that it was Transformers1, the intro to these series, I would like to highlight that it contains a couple or more plot-holes(if that is the correct word for it).
I guess that all is forgiven in the first movie as they needed English to convey the foundation of the story to audience.
Luckily to add to the logical part for the viewers, there's this scene with Prime stating "we used the WorldWideWeb ".
Also,they are advanced beings,not only they pre-date us, but are WAY MORE technologically advanced (a shitty decepticon cracked into NASA and what not).
Some of us viewers(myself included) believe Starscream or any other higher decepticon must have been continuously been communicating with him.
Many others say that it's left for us viewers to guess.