Hi, I was wondering where your info on Richard is from. I can't find anything about him in the convict records I've seen. Also, is your info re: John marrying Margaret Walsh from family history stories? Of course there could be more than one John Bowe marrying a Margaret Walsh, but we do have that marriage record for those names in 1807 in Freshford, where a John Bowe was born abt 1772. It does fit well enough date and name-wise I think to be considered a candidate.
This NW Kilkenny Bowe cluster is known to have spread out around northern Kilkenny and Laois too. My Michael b. 1790 ... there are good pointers he was from Tullaroan yet he left Ireland with his family from just east of Ballyragget, almost in Castlecomer. Many Bowe were farmers and had to move around for opportunity. So your John wasn't necessarily born and married in Castlecomer.
If you and me and fbarbe8 can share what documentation there is for the events we're looking at we can all get on the same page with what is cemented and what isn't. Or maybe it's just me that needs a few source holes filled?