What is important to ascertain when looking into a Shiduch with a child of Geirim? (they went through with a few Geirus procedures, last one -L’eChumra. It’s unknown at which point their daughter was born).
Such matters should not be “self-assessed”, Rather, you should ensure that you receive verification from a Rov (who has specific expertise in such matters) that there are no concerns regarding her status as a Jew.
[Furthermore, even if the parents’ Giyur was proper and the child was born afterwards, there is a separate issue that she cannot marry a Kohen.]