Cybertronian languages

It should be little surprise, given a moment's thought, that distinct Cybertronian languages exist. The Transformers did not go about speaking English or any other known Earth language long ages ago on their distant metal world. Though the records of such conversations are frequently translated for us, we should not forget that these conversations originally flowed in odd electronic syllables past strange metallic lips, or were etched by alien hands long eons before the first humans painted muddy shapes upon dark cave stone.

Fiction

Marvel Generation 1 comics

Runamuck and Runabout sprayed Cybertronian graffiti across Earth monuments. Decepticon Graffiti!

Generation 1 cartoon

So it's true. The Pyramids were built by aliens.

The first language used by the Transformers was likely the Quintesson language inherited from their former masters. It can be seen upon the walls of the Quintesson dimensional transporter room. It rather resembles Egyptian hieroglyphs. Madman's Paradise

Ancient Autobot, on the other hand, eschewed pictures of birdies

Ancient Autobot was the language used by the ancient Autobot colonists that fled Cybertron in the distant past. Most modern Transformers (or at least the Decepticons) could not read it. Cosmic Rust

The controls of the Plasma Energy Chamber were labeled in Ancient Cybertronian, which Spike Witwicky did not recognize but Cerebros was able to read. The Rebirth, Part 1

In contrast, the language used by the Autobots when they first awoke in 1984 was easily learned. Spike Witwicky learned to read Modern Autobot after only knowing the Transformers for a single day More Than Meets the Eye, Part 2

Transformers (2007)

Even with subtitles, it's still hard to understand what he's saying.

Rather unique to this universe, several Transformers (notably Optimus Prime and Megatron) have Cybertronian words etched onto their heads, near the cheek area. What they say is anyone's guess. The All Spark was covered in Cybertronian glyphs, leading Sector Seven to conclude a connection between the All Spark and Megatron. Additionally, cometary forms are covered in Cybertronian "tribal markings".

The Decepticons communicate in Cybertronian (which to human ears appears to be a collection of high-pitched, chirping electronic sounds) when speaking among themselves on Earth, but have learned enough English to communicate with the humans when necessary. The crew members of the vessel Ghost 1 thought that one could make out words if they had a degree in theoretical physics...and were tripping on bad acid. Transformers: Ghosts of Yesterday

Cybertronian languages appear to contain a lot of information in small fragments.

Note: The written version of Cybertronian appears now and again throughout the film, most obviously during Decepticon dialogue, where the subtitles are displayed in Cybertronian briefly before translating to English.

It is also worth noting that this is the first time that Transformers are seen speaking their own language.

Classics

Classics Cosmos is planned to have his name written on his vehicle mode in Cybertronian lettering.