I use the series the hierarchy the same way. The only thing I have gotten to work is to use the integers for the main series and decimal for the sub series does not help for sorting inside calibre. But in sending to device I use this so all the books are sorted properly.
{tags:re([\.],/!)|!|}/{authors[0]}/{authors}/{series:subitems(0,1)||/}{series_index:0>5.2f| | - }{series:subitems(1,10)| | - }{title}
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