From what I understand these conversions are a result of the 40+ years of the liberalizing of morality, that is, women priests, practicing homosexual male and female ministers and now, same-sex married couples with one being the clergy for a parish.
I assume it was an accumulation of the last 40 years of all KINDS of moral relativism that pushed so many Episcopalians and Anglicans to ask the Vatican for a return to Rome..."Crossing the Tiber."
I also understand that these big group conversions will be allowed to keep their Liturgy, with the addition, of course, of Transubstantiation.
The liturgy has been 'tweaked' to make it more authentically catholic and there are other slight changes. You may find these articles informational.
From the Personal Ordinariate of Our Lady of Walsingham, the first one founded in the US.
From Catholic News Service.