Thanks for the template file.
Well, I checked your file, you have set different Fill pattern styles (Format Cells|Fill tab) provided by MS Excel to the cells. You have to select and specify the predefined patterns from the list as I could not find any option to create custom patterns in MS Excel either. If you do find a way to create custom pattern styles, let us know with details and we will check it on how to do it via Aspose.Cells APIs.
Regarding rendering Pattern styles in the output PDF file, well, Aspose.Cells renders pattern styles the way they look into print preview of MS Excel sheet(s). We requested you to kindly try our latest version/fix and let us know if you find any indifferent renderings (please zoom the document to higher percentage values), kindly attach your output PDF files (one by Aspose.Cells for .NET (latest version) and other via built-in MS Excel renderer), we will check it soon.