SSRS 2016 report is failing with 'EXCELOPENXML' render format error
It looks like you have a couple of issues going on here.  


You have the *OPENXML extension paths listed for both the legacy and new versions of both Excel and Word.  It looks like the proper extension paths for the legacy renderers are commented out in your config file.  
The other issue is that you've got the *OPENXML extensions listed with the visibility flag set to false.   


I think if you change the lines listed in your question to the following, all renderer options should show up in the dropdown on the subscription page:

&lt;Extension Name="EXCEL" Type="Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer,Microsoft.ReportingServices.ExcelRendering"&gt;
&lt;Extension Name="EXCELOPENXML" Type="Microsoft.ReportingServices.Rendering.ExcelOpenXmlRenderer.ExcelOpenXmlRenderer,Microsoft.ReportingServices.ExcelRendering"/&gt;
&lt;Extension Name="WORD" Type="Microsoft.ReportingServices.Rendering.WordRenderer.WordDocumentRenderer,Microsoft.ReportingServices.WordRendering"&gt;
&lt;Extension Name="WORDOPENXML" Type="Microsoft.ReportingServices.Rendering.WordRenderer.WordOpenXmlRenderer.WordOpenXmlDocumentRenderer,Microsoft.ReportingServices.WordRendering"/&gt;


More information on the Excel renderers can also be found here.