Yes, this is expected, the current PDF reader has limited usage, it is not designed for high-fidelity tasks.
Please read “Support level for reading PDF format” section on the following page:
https://www.gemboxsoftware.com/document/docs/supported-file-formats.html#support-level-for-reading-pdf-format-beta
Also, please refer to your previous question regarding the future plans that we have:
So in short, we currently don’t have an adequate solution for converting PDF to DOCX, but we plan to provide one in the relatively near future.
Regards,
Mario