Python Api position discrepancies

want to add a signature (base64 or image) using backend apis over it.

If you have an image than you should be able to load it using one of the Image.Create APIs

https://www.pdftron.com/api/PDFTronSDK/cpp/classpdftron_1_1_p_d_f_1_1_image.html#ac98b19bbffd54c4870a9df1e47697568

Then you can pass the Image to SignatureWidget.CreateSignatureAppearance

https://www.pdftron.com/api/PDFTronSDK/cpp/classpdftron_1_1_p_d_f_1_1_annots_1_1_signature_widget.html#a6d172d65bc63efed3db6b9d22969e98d

Otherwise, if you want to have more control, such as text, you can follow this forum post, and SignatureWidget.SetAppearance API