Hi,
I am currently working on (in the background) a conversion of SpreadsheetML to HTML/CSS. One idea here is that you can generate the HTML/CSS for a table or region in a spreadsheet, and then create a DOCX using the HtmlToWmlConverter module. You can then integrate this DOCX into other DOCX using DocumentBuilder.
However, I am only half done with this module – I have coded the SmlDataRetriever, which retrieves the data along with relevant formatting information. One thing that this module does, which will be super important to you, is that it puts together the display value. In other words, it converts from the raw data in the XLSX to the value that you see when looking at the spreadsheet using Excel (the value you retrieve when getting the value using VBA).
It is actually not a huge job remaining to create the HTML/CSS from the data that SmlDataRetriever returns, but I haven’t had the time.
You very well may want to take the same approach – use SmlDataRetriver to get the data, and then generate HTML/CSS from that data, and then generate the DOCX markup using HtmlToWmlConverter. (If you want to contribute this code to Open-Xml-PowerTools, I would be happy!)
But in any case, SmlDataRetriever is what you want to use.
-Eric