I provided a citation for the official 1831 baptism record, so you need not rely on a purported e-mail message.
Here's another one:
"England Births and Christenings, 1538-1975," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:N2XG-JQ8 : 11 February 2018, Adelaide Troutbeck, 09 Jun 1831); citing , index based upon data collected by the Genealogical Society of Utah, Salt Lake City; FHL microfilm 1,469,037.
See image of original record.
The profile would suggest that Adelaide was born in England, had a son in Australia, then a daughter in England, and died in England. Which might be true, but needs sourcing (maybe the proof is on the children's profiles - I didn't dig in).
You have two possibilities: Either the headstone belongs to a different woman, or it belongs to the same woman, but it's incorrect. Can't have it both ways. I would not change it without resolving that discrepancy.
Edit to add: I found some more sources, including Violet's baptism and the 1871 Census showing Adelaide and Violet along with Anne Troutbeck in the same household. (Again, maybe on other profiles already, but I didn't look.) So it seems to be the same woman. Maybe she fudged her age, perhaps because her husband was younger, and no one knew better when she died, so she was buried with inaccurate info on her headstone. Not at all a unique story.
It's still possible that a different Anne Troutbeck had a daughter named Adelaide a couple of years later. Perhaps two cousins named Adelaide, both with mothers named Ann or Anne. I think if you want to believe the headstone, you have to find an 1833 Adelaide birth/christening record. Another possibility is to find two Adelaides in two different Troutbeck households in the 1841 or 1851 Census. Good luck!