Robert Johnston, alias Robert Hanratty

Does anyone know if any trial records for convicts sent to Australia in the 1820’s is still available in Ireland?

I have an ancestor, with a number of aliases.  He arrived in New South Wales in 1827 on board the Ship Mangles 5. He is listed on the Convict indents, twice, once with the name of Robert Johnston, and the other with the name of Robert HAURATLY.  In 1834 he married Ellen Moran and the marriage shows, yet another alias - Robert or Arthur Hanratty per Mangles 5 to Ellen Hanratty per Edward alias Moran, were joined in together in wedlock by me this 19th Day of September 1834.  From checking both the indents for Robert & Ellen, they were both tried at Monaghan, Ireland on the 7 August 1827. Robert was convicted of pick pocketing and Ellen for stealing money.

From the Irish Convicts Database, Robert is listed as being Robert Hanratly, alias Johnston born 1808 in Armagh. He never used the name of Johnston again in NSW after he arrived, though he did use the name Arthur again (along with another surname aliases).

Probably a long shot, but I’d be interested to know if we could establish his true name from the actual trial records and therefore, find his baptism. I know there are 3 baptism’s on ifhf.rootsireland.ie for Robert Johnston, all born in 1808, 2 in Armagh and the other in Monaghan.  Not much luck though with the surname of Hanratty (or variants).