Apologies if the use of "encouraging" is too strong a word for your sensibilities. However, you're skirting the issue.
You know 1 Cor 14:28 states that if a person speaks in tongues in the church, he/she is to speak silently to God if there is no interpretation.
According to you, 1 Cor 14:27-28 refers to "counterfeit (ecstatic speech)" due to the use of the singular "tongue" (Greek glōssē, noun, singular).
So when Paul wrote 1 Cor 14:28 (if there be no interpreter, let him keep silence in the church; and let him speak to himself, and to God), Paul is "allowing" the use of the counterfeit (according to you) to be spoken to God.
We know Paul is not shy. He had no problem telling the Corinthian believers to knock off certain behaviors, but when it comes to (according to you) "counterfeit (ecstatic speech)", this is something Paul allows to be spoken to God? Seriously?
Yes. Paul was able to make perfectly clear that certain behavior was to stop. So why do you think Paul is not so clear when it comes to (according to you) the "counterfeit (ecstatic speech)" you claim was going on in the church at Corinth?
Could it be that Paul does not discuss "counterfeit (ecstatic speech)" at all? And that Paul's focus in 1 Cor 12 - 14 is on the genuine manifestation of the Spirit?
I believe Paul wrote concerning the genuine manifestation when he wrote 1 Cor 12 - 14.
You have yet to establish that Paul spoke of "foreign language" or "ecstatic utterance".
In 1 Cor 14, Paul wrote concerning the use of the manifestation within the church. Paul is not addressing "fellowship with God" in his writing of 1 Cor 14 (or 1 Cor 12 - 13 for that matter).
Believers come face to face with situations in which the manifestation (as shown in 1 Cor 12:8-10) is beneficial at various times ... not just when we are in church.
The manifestation (as shown in 1 Cor 12:8-10) benefits the believer in every instance in life.
According to 1 Cor 14:39, Paul states we are not to forbid speaking in tongues.