You can call it both a transformation or a translation, but that doesn't make 'translation' more appropriate of a term. It is a procedural transformation that can be expressed entirely in a one line function of pseudo-code.

translation from one real language to another is so complex that it cannot even be represented in a hash table. Notably, the elements of grammar and syntax are not present in this naive form of translation. It is also lacking the element of bridging understanding, the root of the word translate.

I would even posit that many CS words that are more appropriate here: encoding, compiling, cyphering, mutating, obfuscating,

Thus insisting on a word where critical elements of that word are lacking and despite the existence of more precise language is itself a poor translation.

"Translate" is an appropriate term, because pig-latin is a language. I.e. you can communicate with it.

The fact that it is an invented, derivative, isomorphic language doesn't mean it loses any properties of being a language.

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Being precise in mathematical or technical terms to a non-technical newbie makes no sense. They need to grasp some basic concepts of what its all about first, in terms that will make immediate sense to them.

Only introduce formalisms when the need for them arises. That way, the reader is not only prepared for them, but can understand the motivation for learning them.

Unless the intro is going to go long and deep, as in the reader is going to become a practitioner, overly precise formalism or language may not add anything at all - because they won't be ready to understand the nuance.

One novel step at a time.

It ends up being easier for the reader, gives them a series of rewarding light-bulb experiences, and requires less explanation in then end. Win-win-win.