I’ve come a long way in my search for answers about Monsieur Pierre Auguste Dutaillis… my greatx4 grandfather…. but so much of his life is still a mystery!

Just this week I finally found the explanation to that particular mystery about him …. in the record book of Scottish marriages from 1751 to 1800 for Edinburgh parish. What a bonus! His occupation is also listed, giving me hope that I can find more information about his early life in France.
There are so many variations of his surname in the records I do have, and his birth year is not given in a single one! We can guess …. if Isabella was born in 1774 … he is likely older than her …. but that’s about it! With a birth year ranging from 1760 to 1774, and the various spellings of Dutaillis … Du’Taille and Dutailly… DeTaille… Dutailles … to name a few, it is still overwhelming. But there is hope.
In pursuit of information on his origins I joined another genealogy web site: one that is French called geneanet.org. This has been very helpful going forward in his younger children’s lives but so far no answers about him. Just more questions.
Four children went with him and Isabella to France in approximately 1817. There is no record of him after they arrive but Isabella’s death record confirms the family did move “home” as do records of marriages and births and deaths for the children.
Who is he??? Why cant I find him?