Unless you REALLY need the libname engine, I would recommend that you use the ExcelXP destination to create your files. That's because ExcelXP writes the kind of XML that Excel "likes" -- Microsoft came up with Spreadsheet Markup Language XML in Office 2002/2003 and ODS has been able to create this specific kind of XML since SAS 9 first came out.
If you use the LIBNAME engine, you get "generic" tabular XML -- and, as you have discovered, Excel may or may not be happy with that form of XML. The only way to change the <TABLE> tag is to modfy the tagset template definition using PROC TEMPLATE.
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