Anglicanism was coined to describe the common religious tradition of these churches; ｛as also that of ｝the Scottish Episcopal Church, which, though originating earlier within the Church of Scotland, had come to be recognised as sharing this common identity.
that = relative (anaphoric) pronoun referring back to an earlier noun or noun-phrase
as = in the same way, similarly
also = in addition, as well, too
and also too that [i.e. the common religious tradition] of the Scottish Episcopal Church
This "Renaissance" of the Latin language (as also that of ancient Greek) did not start any earlier than the 8th-9th century.
as also the "Renaissance" of ancient Greek...
and the "Renaissance" of ancient Greek as well