Issue:

Running DefaultViewer command line on Windows 10 French language does not write CLSID to Registry

Resolution

Update this from the Options menu.  It works correctly when using PowerPDF > File > Options > General > Integrations > Enable View PDF documents in Internet Explorer

When executing the command line with DefaultViewer, it does not give an errors. Check of the registry shows the CSLID did not get written.

Registry location is  HKEY_CLASSES_ROOT\MIME\Database\Content Type\application/pdf.