We don't have synonyms for usherian yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are eutherian, usher in and ushering.
(adj) :
Alternative form of Ussherian. [Of or relating to James Ussher (1581–1656), Church of Ireland Archbishop of Armagh and Primate of All Ireland between 1625 and 1656.]
(adj) :
Alternative form of Ussherian. [Of or relating to James Ussher (1581–1656), Church of Ireland Archbishop of Armagh and Primate of All Ireland between 1625 and 1656.]