A PDF file created by bookcmd=render_article&writer=rdf2latex contains a lot of errors.
Overview

1. Because pages are divided by 2 columns, formulas are overwritten by text or cut off.
2. Graphics aren't positioned where they should.
3. Templates aren't interpreted correctly.
4. <math> contents aren't rendered correctly.

Details
See the related items in appendix 2.

1. Formulas should be indented by <p style="margin-left:4.5em;"> but aren't. See the formula template.
2. The next graphic should be positioned before the following text paragraph.
3. This graphic element is part of a template containing the next paragraph. The graphic should be positioned left to the text (not above).
4. Formulas that are too wide go beyond the text area and are cut off (in column 2) or overwritten by other text (in column 1). That's a direct effect caused by the two-columns text area by default. It's urgently requested to ask the user whether he wants one or two columns.
5. Wikitables are not shown (as well as part of a template's content or directly in the wiki site).
6. \text parts inside a <math> formula that contain more than one word aren't shown in the correct sequence: "mit dem Winkel" is replaced by "Winkel dem mit", e.g.
7. Bold text inside a template is sometimes rendered as light text.
8. Italic text inside a template is sometimes rendered as straight text.
9. One template isn't shown at all. Therefore the reader cannot see where a specific exercise or solution starts and ends.

Multiple occurrencies of the same fault aren't marked normally. (In appendix 2 there are additional faults but not related to the MediaWiki problems.)

How to check the problems

1. Use MathML in user preferences / appearance.
2. de-Wikibooks chapter "Komplexe_Zahlen/_Darstellungsformen" - the requested page (Internet Explorer 11 isn't able to show correct formulas using MathML)
3. Use Print/Preview/Print of the browser (here: Firefox 42.0) - every part of the page is printed correctly (IE isn't able to show any formulas)
4. Use Special:Book render_article rdf2latex and store the created pdf file.
5. Appendix 1 F3079535 is the created pdf file without any change.
6. Appendix 2 F3079554 shows the errors listed above (and contains some more errors caused by convertion to OpenOfficeGraph odg).