I found two problems while using Aspose Cells.
I made a example which explains my problems better.
When I set the page layout to a size, for example 'SRA3', if I force the paper size in code, then save xlsx a paper size is maintaind. If I don't force the PaperSize in the code, format isn't kept.
The paper size isn't propagated from xlsx file by saving it as a pdf file in either case.
When making tests, feel free to modify Test.xlsx