Sorry for your losses.
Taiwan has a very high cremation rate (above 90 percent), so your mother was probably not buried. Still, that’s just a technicality.
You might try calling some of the cemeteries/columbaria around Tainan.
One question, though: In 2009 you wrote “Both of my parents have past away,” which doesn’t fit at all with saying in 2025 that your mother died ten years ago and that your father passed away recently. Why the discrepancies?