NotImplementedException is thrown for GetCapHeight method of CFFFontSource.

System.NotImplementedException: The method or operation is not implemented.
   at Telerik.Windows.Documents.Core.Fonts.Type1.CFFFormat.CFFFontSource.GetCapHeight()
   at Telerik.Windows.Documents.Core.Fonts.FontSource.get_CapHeight()
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontDescriptor.CopyRequiredButType3FontPropertiesFrom(FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontDescriptor.CopyPropertiesFrom(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.CidFontObject.CopyPropertiesFromOverride(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.Type0FontObject.CopyPropertiesFromOverride(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Export.PdfExporter.WriteFontsFromContext(PdfWriter writer, IPdfExportContext context)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Export.PdfExporter.Export(IRadFixedDocumentExportContext context, Stream output)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.ExceptionHandling.ExecutionHandler.TryHandleExecution[E](Action operation)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.PdfFormatProvider.ExportOverride(RadFixedDocument document, Stream output, CancellationToken cancellationToken)
   at Telerik.Windows.Documents.Common.FormatProviders.FormatProviderBase`1.Export(T document, Stream output, Nullable`1 timeout)

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.