As per the description above, you are getting a garbled text when you convert a PDF file to Excel, Is that correct?
Please try to convert the PDF files using the URL https://cloud.acrobat.com/exportpdf and check if it makes any difference.
Try to Export another PDF and check. You may also refer to Text is garbled in converted file | ExportPDF Link: https://helpx.adobe.com/acrobat-com/kb/troubleshoot-conversion-problems.html
Let us know how it goes.
Thanks for your response. I tried to convert a file using https://cloud.acrobat.com/exportpdf. It makes no difference.
I converted around 150 documents, they all share the same structure. I get only minor issues with the text, but significant issues (i.e. more than i can fix with a manual Quality assurance step) with (nested) tables.