You might looking at the Civil registration records which date back to 1864 to find out if Owen died in Aughrim. As to the marriage record that you mentioned, I did not find an 1854 marriage record, but rather an 1856 record in the Baltinglass parish register for a Dominick Byrne and Ann Shorthall of 14 January. This is a Catholic parish register.
I see the transcription of the 1821 marriage record that you refer to for Margaret Fairfield and Owen Byrne's marriage. Aughrim was most likely Margaret's home parish as a bride traditionally married from her parish church. I also noted that their witnesses were: Mary Byrne (possibly a relative of Owen's) and William Doyle.
You are probably aware that there were 5 children born to this couple who were baptised between 1822 - 1835. Those records are on Roots Ireland but they can also be accessed digitally through the National Library of Ireland parish register site. The parish where they were residing was Killaveney,and Margaret Fairfield's name was noted as Madge Fairfield.
Patrick Byrne's baptism record: https://registers.nli.ie/registers/vtls000633993#page/128/mode/1up (left side of the page) 1 March 1822
Sarah Byrne's baptism record: https://registers.nli.ie/registers/vtls000633993#page/145/mode/1up 11 October 1825
James Byrne's baptism record: https://registers.nli.ie/registers/vtls000633993#page/162/mode/1up 29 July 1829
Bridget Byrne's baptism record: https://registers.nli.ie/registers/vtls000633993#page/174/mode/1up 17 June 1832
Edward Byrne's baptism record: https://registers.nli.ie/registers/vtls000633993#page/190/mode/1up 10 May 1835.
The Killaveney register is the parish where this family resided and the writing is very legible on all of the above baptism entries. Killaveney would be the parish that I would recommend you focus your research with Owen Byrne. Killaclorin townland is a residence noted in the baptism records and it would appear that this is where they resided. Just a few things to note: Killaveny is located within the civil parish of Kilpipe which straddles both counties Wexford and Wicklow. https://www.townlands.ie/wexford/kilpipe/
The townland where the Byrnes family resided is Killacloran: https://www.townlands.ie/wicklow/ballinacor-south/kilpipe/aughrim/killacloran/
The Griffith's Valuation link for this townland shows that a number of Byrnes families resided there as well as a Fairfield family:
I also noted from a quick look at the 1901 Census that the Byrnes family name was still associated with the townland. You can use the link for the townland of Killacloran above to access the 1901 & 1911 Censuses. Scroll down to the bottom of the page and you will see the links there.
If Margaret Fairfield Byrnes emigrated to Canada without Owen Byrne, it may indicate that he died in Ireland, or that he left earlier. You can check graveyards for any possible headstone (many famillies could not afford these) through the following websites:
http://www.findagrave.com You can search using the surname of Byrnes and narrow it down by using County Wicklow. St Bridget's Cemetery in Annacurragh, County Wicklow is listed and there are a number of Byrne headstones there.
Here is a link to some photographs for Annacurra graveyard (close to the area where the Byrnes family lived).
I hope that I have not thrown too much information at you, but I wasn;t sure how much information you had. If you have any questions, please email me at: email@example.com
Have a wonderul Easter.
All the best,