NO, your statements are completely untrue---show your documentation please!!
For a breakdown on the actual beliefs, history and worship practices of the Ethiopian, Coptic, Indian and Assyrian (Church of the East), I suggest, from a liturgical standpoint,
Prayer and Worship in Eastern Christianities, 5th to 11th Centuries Edited by Brouria Bitton-Ashkelony and Derek Krueger, which was published in 2017, and
Essays in Early Eastern Eucharistic Praying, edited by Paul F. Bradshaw, and published in 1997, so not quite as representative of the liturgiological state of the art as the latter work, but Bradshaw is highly respected as a scholar, and the essays he compiled are by no means dated. For that matter, although it is considered somewhat dated now, the 1950 classic
The Shape of the Liturgy by Dom Gregory Dix spends much time on the specific issue of the Liturgy of Addai and Mari, which is the main Eucharistic liturgy of the Church of the East, both historically and at present, although there are other East Syriac liturgies.
Fr. Robert Taft described in detail the daily worship services of the East Syriac, West Syriac, Ethiopian and Coptic liturgical traditions in his spectacular work
The Liturgy of the Hours, which to date is, I think, the most interesting and exhaustive treatment of the Divine Office as it is prayed in different churches ranging from Anglican to Armenian.
From a more general perspective, the
Blackwell Companion to Eastern Christianity provides a history and a description of the historical and contemporary practices of the Eastern churches we have discussed. I have not yet found a good in depth reference on the subject of Waldensians, but several books concerning Gnosticism address the Albigensian and Cathari Gnostics and the closely related Bogomils of Bosnia and the Paulicians in detail. All of the above are also discussed at length in the now somewhat dated
History of Christianity, volumes IV-VII, by Philip Schaff.
If you can afford it, there is also the
Cambridge History of Christianity, which is more modern and impressive, and Oxford, not to be outdone, recently published a
Handbook of Christian Worship, which provides a high level overview of the history of worship practices throughout Christendom.
There are some additional works I could cite and probably will at some point; I am reading an in depth history of the Moravians which does touch on the history of the Waldensians, but there is a demand for a good history of early Waldensianism specifically; the data to compile such a work is there, to be sure. Unfortunately the Waldensians have never been a substantial presence in the UK, or else there would certainly be an Oxford Handbook on them (as there are on Anglicans, Quakers, Methodists, the Book of Common Prayer, and Christian Worship as a whole).