Precisely - “interpretation” is the translation of what is typically the spoken word (as opposed to the written) from language X to language Y.
Exactly – Corinth was a multi-cultural and very linguistically diverse city. Greek was the ‘native’ language to Corinth, but despite its status as the “English of its day”, not everyone spoke it well enough to be marginally fluent. Again, to my example – if I came from Briton, showed up and start speaking my native language
ain’t no one there gonna understand a word I’m saying; to them, I’m speaking mysteries even though I am earnestly praying from deep within my being (i.e. praying in the Spirit). No one understands me; thus it seems, I am speaking only to God (who understands all languages) and not to those there ("not to man"). Nowhere does it even remotely suggest that the speaker does not understand what he is saying.
2) For he that speaketh in an unknown tongue speaketh not unto men, but unto God: for no man understandeth [him]; howbeit in the spirit he speaketh mysteries.
14) For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful.
I would argue that for tongue-speakers, it can ONLY ever mean that the speaker does not understand himself; else the premise of a “prayer/heavenly/angelic” language fails.
As one internet writer put it, rather bluntly I might add, “You want this to be real. You’ve convinced yourself it’s real. You’re improvising the sounds, but there is nothing about what you’re doing that cannot be explained in natural terms. The only reason it sounds like a language is that you want it to sound like a language. But it’s not. It’s meaningless. You’re not producing a language.”
The above is admittedly a somewhat harsh statement from a former tongues speaker, but the bolded section is 100% true.
Tongues are something concrete that can be tested and analyzed. Again, record yourself for about a minute the next time you speak in tongues. Play it back several times and really listen to what is being produced.