Hello,
We recommend you to read the good practices when working with the conversion plugin available on:
https://www.phpdocx.com/documentation/conversion-plugin/preparing-the-templates-for-its-conversion
For example, you must use specific width values for tables, rows and cells (instead of using automatic values). And use the conversion plugin based on LibreOffice to get the best output.
If you need more tips to get the best output you can send both files (DOCX and PDF) to contact[at]phpdocx.com and the dev team will check them.
Regards.