The first broadcast detected from the anomaly was very brief and primitive. Short enough to be quickly translated, yet effective enough to get the point across.
"Peace. Human. Communicate."
Their transmissions would eventually evolve into their current, more complex forms. The initial transmissions were designed to be accessible to a broad range of civilizations, even those with simple radio capabilities. After realizing our current point in technology, their transmissions were able to better cater towards our computer systems. This had a strong impact on the efficiency of our communication process.
It was quite lucky that our universes shared the English language, as that is what sped up the understanding process. The communicators from the other side of the fold have established contact with many parallel universes besides our own. According to them, our universe is one of few where English happens to exist. English is by no means a required language when it comes to other universes making contact with the anomaly, but it is helpful.