Thank you for considering Aspose products, and welcome to Aspose.Cells support forum.
First of all, we would suggest you to give our latest version of Aspose.Cells for Java a try on your end, as we have evaluated your presented scenario on our end, and was unable to see any problem. Please check the resultant PDF file as attached.
Moreover, please check if the fonts used in the spreadsheet are present on the machine where conversion is taking place. Please note, Aspose.Cells for Java API requires these fonts to render the results properly, and it is suggested that you should explicitly tell the API where to look for the fonts on your machine by using the CellsHelper.setFontDir method at the start of your application.
In case the problem persists, please provide us your environment details such as Operating System version, Operating System Architecture (32bit/64bit), JDK version etc in order to re-evaluate the problem.