Wow!! I've been busy and didn't have the time to take a look here for a VERY long time!! 
Thats really interresting!!!!
Here are some stats from the PR, and HDST above, that may help you in your research.
The father, Patrick Muckedon, on the HDST is born at Winetown Westmeath Co Ireland in 1782, and age 60, dies in 1842. His wife Anne Dealey is born 1794, dies, age 48, in 1832.
The wife of William Muckedon, Catherine Duffey, is born 1812, and, age 46, dies in 1858.
There has been some controversy about her DOD because the HDST appears to show 1838. Well, that is clearly not correct because we know from the PBR she bears two children after that date. Too, her life years are consistent with what we should expect from the life years of her in-laws, Patrick and Anne Muckedon.
Worth mention, the Parish records up until the 1830s are written in Latin, not English. And it does not help that the community is yet Gaelic speaking, not English.
Now, your family record, as set out in the US McDunn book shows Thomas born Nov 1825, of Patrick McCudden and Mary O'Donnell. Need now to find a BR for Patrick McCudden, unless I am misreading the data. Certainly he should show up in the BR sometime close to, or after 1814, because Anne Dealey was just then 20 years old. But she could have conceived as early as 1810, 16 years old.
Although reading the following generations of the Muckedon family it is interesting that only one of them chose to modernize their family name as Patrick McCudden did, and at such a early date. Perhaps it is adopted from Church practice where this spelling is chosen by authors instead of that reported them by respondents?
Later as they begin to write down what is reported them there arises a lot of variety. My research clearly shows considerable confusion there, some adopting very odd translations of Muckedon on vital stats, B M D, e.g McKedon, Mochadan, Muketin etc. Indeed officials appear to have accepted offered names rather than, as earlier, guessing them from their own experience. So we have dozens of different English spellings of it. But by far the most common is McAden, which is the same as that adopted in Scotland by the root family.
Indeed it is precisely because of the form of the original name that we know the Westmeath Muckedon originated in Scotland, and not, as the worthy Latin scholar PPs, their Curates, assumed, Armagh Co., Ireland .
Too, since there are now DNA matches across these families, there is no need for a records proof of kinship.
Finally attached a PBR 1823, Russagh & Rathaspic, Co Wesmeath, Ireland, where Rose McCudden is listed as a sponsor at a Baptism. This is the only one I can find in that records book. I have not looked in the next series but you may if you wish.
https://registers.nli.ie/parishes/0176I hope that helps you with your research.
