We have tested all the sample files provided by you and getting following warning only:
ignoring UTF-8: not a valid region tag
** (process:988): WARNING **: 08:32:43.900: NOT IMPLEMENTED: GdipWidenPath
We have observed this issue but we need to look into it more. We have logged the issue in our database for investigation and for a fix. Once, we will have some news for you, we will update you in this topic.
This issue has been logged as
CELLSNETCORE-14 - Warning raised while converting XLSX/XLSM to PDF
I have also recorded the following warning message in the ticket for our reference:
** (process:6255): WARNING **: Requested 0 bytes. Maximum size for region is 262144 bytes.
Regarding the larger text issue, I have converted PC 341710.xlsx to PDF using Excel 365 and observed that output PDF also contains large text. This seems to be issue with the source Excel file. You may please try it at your end and provide us some sample file which can be converted correctly using Excel but not by Aspose.Cells. We will analyze it and provide our feedback.