Christina was born about 1806.
Unconfirmed, but this is likely to be Christina in the 1870 census: https://www.familysearch.org/ark:/61903/1:1:MZLJ-BDG
The name is "Christian", but the gender is female and the occupation is "housekeeping", so it's probably a typo. Birth year in 1798 and location in Longswamp matches the unsourced family information. It's also possible that that unsourced information originally came from this census, in which case there's no supporting information to tie this profile to that census record.
This document refers to Benjamin Weidaw's wife as "Christina Oswald", born in1806 in Longswampt, Berks Co., PA. According to the same notes, she married Benjamin Weidaw about 1820 in Bowmanston, Carbon Co. PA. However, all other information about Bemjamin Weidaw gives his wife as "Christina Anewalt".
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The 1860 census shows what looks like a "Christianna Weidaw" age 61: https://www.familysearch.org/ark:/61903/3:1:33SQ-GBSD-HZF
This may be her again in the 1870 census: https://www.familysearch.org/ark:/61903/1:1:MZLJ-BDG. The name is "Christian", but the gender is female and the occupation is "housekeeping", so it's probably a typo. Birth year in 1798 and location in Longswamp matches the unsourced family information.
Ancestry.com appears to have a copy of her death certificate, but it's paywalled and I haven't found an alternative yet. "Pennsylvania Historic and Museum Commission; Pennsylvania, USA; Pennsylvania, Death Certificates, 1906-1965; Certificate Number Range: 020251-024140". It's paywalled though. https://www.ancestry.com/search/categories/34/?name=Christena_Anewalt
I had no luck finding her marriage record, despite the family knowledge suggesting that it was in 1820. If we can confirm her last name at birth, I can merge the profiles.
A quick glance at the sources looks like it's all christenings of children. For example: https://www.familysearch.org/ark:/61903/1:1:HWKW-TM3Z. It also suggests the marriage was in 1818 rather than 1820. Probably because a child was born in 1819.
Unfortunately the underlying source is a large set of images and I don't see a way to find the relevant one. It's also likely that since she was married at this point, it won't be helpful for finding her maiden name.
Finding the death certificate (or someone who pays for Ancestry access) is the most likely way to resolve this.