Could meta also mean "beyond"?
Sure, it means with, after, behind etc. The compound expression mentanoia cannot be understood as a raw product of its component words any more that the English word understanding, which—if translated literally as under+standing would translate into Greek as hypo+stasis, and into Latin as sub+stantia!
Such literal translations almost always, if nto always, lead into theological errors, as is the case with the translation of the Greek hypostasis (which represent a form or sui-generis reality or existence), first being translated into Latin as as persona (a mask!) and from there into English as person, although literlly i translates into substantia.
Of course Latin substantia (substance, matter) is completely unrelated to the Greek hypostasis, but it is a literal translation of it! It actually corresponds to the Greek ousia (essence or nature), as in homoousios (not homoiousios!) when the Creed speaks of the Father and the Son being of the same substance.
So now you have all western Christians speaking of three "Persons" of the Godhead (which itself is a mistranslation of the Greek theotes).
An even better exmaple, and one of my favoirtes, is in Irenaeus' Latin translation (from the 4th centuy AD) in which he referrs to Mary (the Mother of God) as the advocata (Latin for intercessor, adviocate, lawyer). But when this word is translated into Greek, in which IOrenaeus originally wrote (the roiginal is lost) it read as Paraclete (Holy Ghost)! I doubt that Irenaeus thought of, or confused Blessed Mary with the Holy Ghost! :)
Going back to the compund words, while some compound words can be translated simply by adding the meaning of the component words (such as fore+see), most of the time you can't. Thus, mentanoia (to repent), and metamelomai (to regret, to be sorry, literally after+care, to mind as an afterthought) are not identical.
Botom line is this: many Greek words have very specific meaning in terms of an unwritten finesse rather than an etymological or lexical value. Thus, bapto and baptizo come from the same root meaning to submerge, or to dunk, but baptizo came to mean repeated dunking resulting in permanent change (as in pickling a cucumber). Naturally the Church chose baptizo to represent christening or baptism rather than bapto!