Steganography in speech by adding extra "filler" syllables
To the extent that I think this is a cryptographic question (which I don't!), I don't think these language games qualify as steganography.  Steganography conceals the existence of a message by encoding it into (hopefully) undetectable modulations of another message, which is meant to appear innocuous to an adversary.  As Wikipedia puts it:


  The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny. Plainly visible encrypted messages—no matter how unbreakable—arouse interest, and may in themselves be incriminating in countries where encryption is illegal. Thus, whereas cryptography is the practice of protecting the contents of a message alone, steganography is concerned with concealing the fact that a secret message is being sent, as well as concealing the contents of the message.


But languages games like Pig Latin or jeringonza don't generally fool adversaries into thinking that the message is innocuous.  Some of these games produce output that is linguistically very marked.  For example, Hola amigo is pronounced ['o la 'mi ɣo] (International Phonetic Alphabet; stressed syllables are prefixed with apostrophe as is standard), with broadly trochaic stress (LOUD-soft-LOUD-soft) as is typical of Spanish (default penultimate stress).  But Chi-ho chi-la chi-a chi-mi chi-go, as in the Caribbean variant of the jeringonza game, is strictly iambic (soft-LOUD-soft-LOUD): [tʃi 'o tʃi 'la tʃi 'a tʃi 'mi tʃi 'ɣo].  So this particular language game produces outputs that are systematically different from regular Spanish phonology.  Nobody's gonna mistake this for small talk about the weather.

And while I stress that I don't think these language games are properly cryptographic, if anything they often resemble ciphers more closely than steganography.  One capsule explanation of modern cryptography is that it achieves security by transforming messages using trapdoor functions—schemes where messages are transformed in ways that are cost-effective to honest parties but prohibitively expensive for adversaries.  And if you squint really hard these language games approximate that paradigm—they transform a message in a way that the ingroup has mastered through practice (dare I call this "precomputation"?) but the outgroup hasn't.