This was noticed by @nilgun that the conversion from <para> to <simpara> is affecting the layout of pages.
Indeed, two consecutive <simpara> tags are rendered as one big paragraph, which is not what the XML markup indicates.
I don't understand why the choice was made to deviate from the usual conversion to HTML <p> tag, as flow content is allowed within a <dd> HTML tag.
This is a quite simple fix, and should better represent the behaviour intended by the XML, as if someone wanted to only have one big paragraph they wouldn't use multiple <simpara>/<para> tags.