In your first example, it does not say he does nto interpret them, so that is a weak argument, (forgive me, but that is how I see it)
It is always good when you post a whole passage to get context.
So in the second, to get context...
1 cor 14: Therefore let him who speaks in a tongue pray that he may interpret. 14 For if I pray in a tongue, my spirit prays, but my understanding is unfruitful. 15 What is the conclusion then? I will pray with the spirit, and I will also pray with the understanding. I will sing with the spirit, and I will also sing with the understanding. 16 Otherwise, if you bless with the spirit, how will he who occupies the place of the uninformed say “Amen” at your giving of thanks, since he does not understand what you say? 17 For you indeed give thanks well, but the other is not edified.
Pauls conclusion is that if you pray wiht an unknown tongue and do not have an understanding it is UNFRUTFUL (which has been my argument all along, how can you be EDIFIED in an unfruitful action? You can’t. It is meaningless.
So what was pauls conclusion.
IF I pray, I will understand, IF I SING, I will understand. Otherwise. Not only when I pray is it unfruitful, but when I sing in a tongue when no one understand what I or we are singing thus NO ONE is edified.
Thats also why I say, when people give me examples. I give them the same example except remove tongues from the equation, and ask which example more edified the congregation or the person.
Of course, One guy got mad at me when I did this and ignored me, said I offended him (even though in his example. He said he would take his example to a judge and be vindicated!) as if it is was totally ok for him to offend me.. Again, This is why some people are so against this, it is the attitude of people. Not the actual gift itself.
In your third, Take it in context of your second. They all fit together.
Thank you for peacefull conversation though.. It is well welcomed!!