The content is cut right side as it does not fit given horizontal space, defined by htmlWidth parameter.
htmlWidth can be seen as a frame width of a virtual web browser.

The simplest solution is to scale down the content to match the space.
It can be done by an increasing of htmlWidth conversion parameter value.

Alternatively you may rotate particular pages from portrait to landscape orientation to win some extra horizontal space.

See http://pd4ml.com/cookbook/pdf_dynamic_format_change.htm

Also there is a method adjustHtmlWidth() http://pd4ml.com/api/org/zefer/pd4ml/PD4ML.html#adjustHtmlWidth()
It tries to dynamically determine htmlWidth parameter value to let the content fit. But it is not efficient in all the cases. And by really wide content it may lead to tiny unreadable font sizes.