I don't think you can get that from what I said. However if you did, I agree with you that is not how it works.
Now as to the benefit Paul saw in praying in an unknown tongue when his spirit prayed but his understanding was unfruitful.
I don't think any of us can clearly explain the mystery behind prayer. Why we are asked to pray when God already knows what we need. We don't have to understand why we just do it because it is God's method and plan that we do it. We do not fully know what happens when we pray in the spirit but our understanding is unfruitful but we do it anyway.
If it is NOT because we are praying about things we do not understand needs to be prayed for, then it is for some other reason, that we do not understand. For one thing we can be certain of is that our understanding is unfruitful. Howbeit we do it anyway.
1 Cor 14: 14For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful. 15What is it then? I will pray with the spirit, and I will pray with the understanding also:
Also, for the benefit of those who respect non pentecostal theologians like F.F. Bruce enough to have an open ear to hear what Paul was talking about please see the below excerpt from F.F. Bruce commentary on Romans 8.
26. The Spirit himself intercedes for us. He is called the disciples’ ‘advocate’ (paraklētos) in John 14:16, 26; 15:26; 16:7 (see also note on verse 34, below). Cf. Ephesians 6:18, ‘Pray at all times in the Spirit, with all prayer and supplication.’ When believers pray ‘in the Spirit’, the Spirit himself intercedes on their behalf. (See p. 57.) With sighs too deep for words. ‘Through our inarticulate groans’ (NEB). The noun stenagmos, like the verb stenazō (used in verse 23), may denote either sighing or groaning.
Speaking to God in the Spirit with ‘tongues’ (1 Cor. 14:2) may be included in this expression, but it covers those longings and aspirations which well up from the depths of the spirit and cannot be imprisoned within the confines of everyday words. In such prayer it is the indwelling Spirit who prays, and his mind is immediately read by the Father to whom the prayer is addressed (verse 27). Moreover, these ‘inarticulate groans’ cannot be dissociated from the groaning of verse 23, with which believers (together with all creation) express their longing for the coming resurrection-glory, which will consummate the answer to all their prayers. (See p. 58 with n. 77.)
Bruce, F. F.. Romans (Tyndale New Testament Commentaries) (p. 175). InterVarsity Press. Kindle Edition.
So as you can see in the sentences in red that Bruce sees a connection between what Paul was referring to in praying in tongues and that separate subject of the groanings which cannot be uttered. They are not the same but the REASON might be the same. That just as the Spirit prays through us with groaning that cannot be uttered which in that context specifically says "because we know not what we should pray for as we ought" Bruce is saying that this praying in tongues that Paul did where his understanding was unfruitful was probably also for the same kind of purpose. Now many non pentecostals will agree with F. F. Bruce and I wanted to point out that he is intellectually honest about his interpretation of scripture even though he was not a pentecostal. He was far better at hermeneutics and interpretation of scriptures than anyone on these forumns including myself.
There is much benefit to praying in tongues and interceding in tongues. As a matter of fact all those who have recieved this gift and have prayed in tongues in private for thirty minutes have testimonies of experiencing a spiritual charging, and that when they get immediately into the study of the Word of God after such an intercession time they experience illumination that is beyond their normal bible study experience without praying in tongues for 30 minutes. It is obvious to those who experience these benefits that something awesome happens from praying in tongues that enables them to have understanding in the scriptures, a concentration, a quick recall of other scriptures that contribute to a sudden illumination of a theological concept that they realize was there all along but they had passed over it many times without the light turning on. Their heart burns within them as the see JESUS revealed in Old Testament scriptures and they KNOW it is a direct result of praying 30 minutes in tongues before they started their study.
I hesitate to share these precious benefits in a forum like this because afterwards I cringe at some of the statements that people will make as they proceed to trample on these precious pearls. Please don't be that guy.