When a worksheet has name that has spaces and a hyperlink to this worksheet is being inserted in Excel, quotes are used to surround the name (ex: 'Sheet 12'!A1) for a valid hyperlink. If quotes are not added, the hyperlink is invalid.
In RadSpreadsheet, it is the opposite: (Sheet 12!A1 is correct, while 'Sheet 12'!A1 is incorrect).
Thus, opening such an exported document from RadSpreadsheet in Excel loads it with incorrect hyperlinks; and importing such an Excel document in RadSpreadsheet loads it with incorrect hyperlinks.

A way to workaround this issue is to modify the hyperlinks on import/export from/to RadSpreadsheet. You can find attached a project demonstrating this approach.

LineInfo objects are not cleared when there are tables in the document being exported to PDF which leads to OutOfMemoryException.

Add support for array formulas (CellFormulaType "array"). These formulas can accept as parameters and return results containing whole arrays (one- or two- dimensional) of data. In MS Excel, such formulas are inserted with CTRL + SHIFT + Enter, and visualized enclosed with curly brackets ('{' and '}').