I've looked into the encoding of annotations that make up the check boxes and radio buttons. The check boxes are using ZapfDingbats for the checks. You will need to install or stage the dingbats.pfb font from http://svn.ghostscript.com/ghostscript/trunk/urw-fonts/ on your Linux system.
The FontManager class will scan the following locations on a linux system for available fonts.
"/etc/fonts/",
System.getProperty("user.home") + "/.fonts/",
"/system/etc/fonts/",
"/usr/lib/X11/fonts",
"/usr/share/a2ps/afm/",
"/usr/share/enscript/afm/",
"/usr/share/fonts/local/",
"/usr/share/fonts/truetype/",
"/usr/share/fonts/truetype/freefont/",
"/usr/share/fonts/truetype/msttcorefonts/",
"/usr/share/fonts/Type1/",
"/usr/share/fonts/type1/gsfonts/",
"/usr/share/fonts/X11/Type1/",
"/usr/share/ghostscript/fonts/",
"/usr/share/groff/1.18.1/font/devps/",
"/usr/share/groff/1.18.1/font/devps/generate/",
"/usr/share/libwmf/fonts/",
"/usr/share/ogonkify/afm/",
"/usr/X11R6/lib/X11/fonts/",
"/var/lib/defoma/gs.d/dirs/fonts/",
If you are using the Viewer RI or the FontPropertiesManager you will need to delete the ~/.icesoft/icepdf-viewer/pdfviewerfontcache.properties so that a new one can be created on the next run of the application.
On a site note our 5.1 development work will bring forms support allowing your sample files forms to be dynamically toggled with the mouse.
Added another file. Which shows similar issue.