Are sparklings/baby robots purely fanon or is there any root in canon?
“Sparkling” is a fan-originated term that recently made the jump to canon when Metroplex called Windblade “Caminus’s sparkling,” to denote that she had been born from the hot spot the Titan carried within him.The term would logically apply to all Transformers born from the different Titan hot spots, and you could probably even call an ordinary Transformer a “sparkling of Cybertron” or something. A euphemism for “child” but not in the literal “actually a baby” sense.
There have been a few instance of “baby” Transformers even from comparatively early in the franchise, with probably the most notable being the “Baby Dinoforce” from the Victory manga. Like a lot of the manga’s more offbeat concepts, though, they were really just there for a cute comedy moment, and not someone one should look at too deeply.
Since the introduction of protoforms in Beast Wars the idea of a Transformer “life cycle” has become more common, with protoforms as the “newborn” stage. They’re typically depicted as coming into being “fully formed,” though, either emerging from Cybertron’s matter or being built by other Transformers, then quickly taking shape and basically just getting on with their life. The live-action movies, though, have shown them being “grown” in energon sacs; we’ve only ever seen them in half-formed states, their hindquarters just a tangle of wires, deprived of the necessary energon to grow them to full size. It seems like they’re not meant to come out until they’re fully grown.
IDW’s gone a little further; there, protoforms start out as simple geometric shapes that grow into robotic forms, sprouting limbs and the parts of their “natural” alternate mode as they do so. The growth process is over very quickly - the alt mode starts to be apparent within hours - but as they grow they do resemble “babies.”