the RCIA ritual book comes from the universal Church and contains adaptations by the bishops of each country, so the book sold in the US is written with those in mind, but NO it is not something concocted by the US bishops
I will not respond directly to your other points which are mainly drawn from personal experience and therefore not valid as a criticism of the RCIA per se as envisioned and promulgated by the Church
Please decide if this is going to be another personal experience thread, which certainly has value for those going through RCIA, or a critique of the RCIA itself.
Bringing up parishes who implement the RCIA improperly, have flawed catechesis, flawed catechists, and misinterpret the rites is not helpful if the purpose of the discussion is to analyze the RCIA itself.
forgot to say, Welcome Home
in the several parishes where I have served in RCIA ministry for over 20 years the after Easter mystagogy and follow-up is excellent. What is woeful is the lack of participation the part of the neophytes. I can guarantee and everyone without exception I know of who is involved in RCIA says the same, that those who do not participate in mystagy have a better than 90% chance of leaving the Church within 5 years. It is without doubt the most critical part of the process as you wisely observe.