Okay I started reading and then quit, ugh. Now I will quote from a first class scholarly resource J. Stone's "Original Enlightenment and the Transformation of Medieval Japanese Buddhism" . This book is truly excellent as she sums up very complex ideas in mere sentences.
First T'ien-tai vs. Hua-yen:
In contrast to Hua-yen emphasis on all things arising from the mind, early T'ien-t'ai - as well as the later T'ien-t'ai thought of Ssu-ming Chilh-li..who attempted to counter Hua-yen influences - denise that the mind is a pure, undifferentiated cosmic principle from which all things arise. In the words of Chih-i...."One may say neither the one mind is prior and all the dharmas posterior nor that all dharmas are prior and the mind posterior. All one can say is that the mind is all dharmas and all dharmas are the mind. Therefore the relationship is neither vertical nor horizontal, neither the same nor different." p. 8
"Hua-yan thought sees all phenomenon as expressions of an originally pure and undifferentiated one mind." p. 7 ..."the Yogacara model in which differentiated phenomena arise from seesd stored within the alaya-vijnana and are independent of suchness."
Chinese thought via The Awakening of Faith" introduced the idea of tathagata-garba the idea of an originally pure enlightened mind intrinsic to all sentient beings, conceptualized as the 'wond' or 'embryo' of Buddhahood" p. 5
"Within the Indian Mahayana, this question has been addressed most explicitly by the Yogacara doctine of the alaya-vijnana or "store consciousness". ...."Ignorance has its source in the defiled seeds that have accumulated in the store consciousness since the inconceivably distant past. Only their thorough extirpation can transform and purify consciousness, a process thought to require many successive lifetimes - three incalculable aeons being a common estimate." p. 5-
So you see there are 3 traditions: Yogacara, Madhyamaka and tathagara-garba
Hope this clears things up.
FYI Hosso supposedly did support the Yogacara idea that some beings could not acheive Buddhahood, but I believe Jokei modified it so that these are beings who don't want
to ever embrace Buddhism, so it's their choice.