Re: Mushaf Fatima, Al-Jamia, and Al-Jafr did exist.
as far as the akhbari thing is concerned one should be aware of this fact that how were they tackled (with evidence, even some public debates took place in this regard), and what were the endurances of our scholars back then, these days you may find them scattered, and you attribute the so-called doctrine of Tahrif (as you said akhbari have/had it) to the entire nation who stood against them, and generation and generation of scholars... moreover, akhbari and usooli is more of a difference like muqalid and ghair-muqlid... .