DejaVMUni.ttf
DejaVuSans.ttf
are usually under tomcat / vsphere-ui webapp / WEB-INF/classes/resources/fonts
Please check if the files are there. I also recommend upgrading to 5.7 - there are new capacity views that you can use for reports. See Now Available: vCenter Operations Manager 5.7 | VMware Virtualization & Cloud Management - VMware Blogs
Thanks,
Alex D.