Overlooked by many is that are "diverse kinds of Tongues". Paul writes hypothetically about "although I speak with the tongues of MEN and of ANGELS" and some say that there are no angelic tongues, that all tongues are human languages unknow to the speaker. The thing is -- Acts 2 does not exhaust all the diverse kinds of tongues, and Paul writing hypothetically does not preclude the possibility that he COULD have spoken in angelic language (he said "I speak in Tongues more than ye all")
Yes, God understands them all. Can Satan counterfeit the gift? Sure. Do people counterfeit money? Yes. Does that mean throw away all your currency because it can be counterfeited? Of course not.
The "prayer language" of a Christian speaking to God need not be interpreted, an utterance IN THE CHURCH in Tongues as a message to the body requires an interpretation, iow, an utterance to the body needs interpretation into the language of the assembly.
Some do not understand this concept of DIVERSE KINDS OF TONGUES and when they make declarations about "this can and cannot happen anymore" they are like "blind men describing the elephant" in that they touched one part of the elephant and concluded that that was all the elephant was. Charismatics have SEEN THE ELEPHANT.