"....He married Sarah Bull in Launceston, Tasmania, in August 1853"
"....His marriage certificate states he was born in New York, circa 1830"
Do you mean that the Tasmanian marriage certificate has his birthplace stated ?
Tasmanian marriage certificate in 1853 would not have provision for birthplace so I wonder why this would be recorded.
"....His death certificate states he was born in Devonshire, England".
"....On his death certificate it indicates he was born in USA"
Can you clarify which birthplace is on the death certificate please. Also does it name the informant, if not, is wife Sarah still alive at the time of his death.
Where there is different information on the birth certificates for fathers birth place, who is the informant. Is there any pattern here ie. when mother is the informant, or when father is the informant?.
On the marriage certificate for 1853 in Launceston, who are the witnesses.
Among the thirteen children are there any less common names or unusual spelling of names?
When he is admitted to hospital the information might not have been provided by Arthur, depending on what sort of condition he was in. Is Arthur the informant.
If Arthur wanted to be evasive about his origins then it will be hard to know the truth. But if he just had a adventurous life, with much storytelling, then his audience might have selective memory in repeating his story...for BDM certificates, for example, where he is not the informant. So the source of these details might be as significant as the substance.