AZ – I see a few of the questions threw you off, as they didn’t fit into any of the talking points you are fond of repeating.
Rav Miller said a Beis Yaakov girl should be wed at about age 17 or 18 (“soon after or before graduation.”) Indeed you are correct that the R”Y’s letter does not disagree with Rav Miller’s position.
Please do faithfully ask Rav Simcha Bunim Cohen and report back to us. How long do you think this will take for you to report back what he says?
I see you have no answer for how we managed for 1,000 years. Why do you say “There is NO reason to think this was around at the time of the rishonim and achronim.”?
Throughout our history the age gap between couples has in fact been larger than currently. Indeed before the war it was not very uncommon for a significantly older male to marry a very young female.
As a completely aside point you made (which is completely wrong), what “incorrect advice” Gedolei Yisroel “asked mechila” for? Which Godol (name at least one) “asked mechila”?