We have designed BuildVu to focus on display accuracy, file size and rendering performance, and do not recommend (or support) modifying the converted documents.
PDF (Portable Document Format) is a file format that is designed for a fixed-layout document display. Its core strength is the accurate rendering of documents across platforms, and by its nature, it is not designed to facilitate the editing of content.
This can present something of a challenge when converting to HTML5, as it is not possible to reliably insert structure that did not originally exist in the file. There is also an inherent challenge when translating from one format (or language) to another that sometimes adjustments must be made when there is no direct translation.
It is for this reason that we have designed BuildVu to focus on display accuracy, file size and rendering performance as opposed to generating content for the purposes of editing.