Hello
i also get these long Tags. I played a while with some epub files i have.
In my case it happens when i open a book in which the css of the text is in the Tag. f.E.
<p ALIGN="JUSTIFY" STYLE="margin-bottom: 0cm; line-height: 100%"><span LANG="zxx">
comes out as:
<p class="sgc-2"><span xml:lang="zxx" xmlns:xml="http://www.w3.org/XML/1998/namespace">
cu