This thread feels a bit like a straw man to me. Historically, Pentecostals have considered tongues to be...at least primarily... human languages. That was the belief of early Pentecostals. There are many accounts from early in the Pentecostal movement, from the Azusa Street revival and other meetings, of foreigners going into meetings and hearing their native languages 'in tongues' at Azusa. There are accounts of Japanese or Russian being spoken 'in tongues.'
Some of the early participants in the Pentecostal movement believed they would be able to do missions work without any language training. This was based on assumptions of how things worked, not taught in scripture. There is no indication that the disciples in Acts 2 could make the language they spoke be the language of an onlooker, and in I Corinthians, others present did not understand the tongues as their native language. We know the disciples were speaking of the wonderful works of God, not if they were preaching Christ or explaining salvation in tongues. The listeners were saved after hearing Peter preach the gospel, presumably in a common language rather than 'in tongues.'
Early in the Pentecostal movement, AG Garr went to India hoping that speaking in tongues would work out as an evangelistic language after someone had identified the tongue he spoke in as Bengali, but this did not happen again for him in India.
But still there have been many accounts of individuals understanding speaking in tongues in their own native language sense. I know there are many accounts of such things, and have been, among Assemblies of God missionaries. Charles Greenoway was a denominational official in the A/G in the 1980's and he had a testimony of someone preaching in tongues and the audience understanding. I know a missionary who spoke in tongues at an outreach to the Cherokee, and the people asked him how he knew their language. DennishBalcombe has told of hearing speaking in tongues 'in English' among Chinese villagers. I spoke with his daughter after a church meeting at a Chinese bilingual church and mentioned that, and she had heard a little grandma in a Chinese village speak what sounded like a psalm in English.
I am not sure where the idea of tongues a spiritual code language came in. I wonder if some of the academics, maybe mainline Protestant Charismatics and WOFers teach that, because I have encountered people who believe that way online and to a lesser degree in real life. But from what I have read, early Charismatics in the US-- I mean in the 1960's believed in tongues as real languages.
I say Pentecostals primarily believe in tongues as real languages because Paul writes, 'Though I speak with the tongues of men and of angels.' Considering the context, it would not be reasonable to reject the idea that such a thing was possible. There was a contemporary Jewish belief that tongues spoke languages, which shows up in some of the apocrophyl or psuedapigraphil writings, references to Job's daughters being given a golden box with a cord that enabled them to speak in such languages. This argues against the idea that Paul was using the term to refer exclusively to Hebrew.
There are those who will insist that 'tongues of angels' are hyperbole and Paul did not really mean that, but if we look at the other parralel arguments he made, it is possible to give all to the poor, to give ones body to be burned. And whatever it means to move mountains whether a metaphor or literal, it is possible for a believer to do that by faith. Paul is listing 'extreme things', so there is no strong basis for saying tongues of angels could not possibly be spoken.
I cannot speak for all Pentecostals and Charismatics, but I suspect just about any Pentecostal who thought of tongues as real languages and came across this passage makes room for the idea of tongues of angels, especially since he doesn't have a motivation for explaining away the verse.