Are you sure editor variables are being expanded in Oxygen 15.2? I used the $framework editor variable in the ant path and I get the following in the console output:

"${frameworkDir}/../../../../tools/jdk/bin/java" -Xmx256m -classpath "${frameworkDir}/../../../../tools/ant/apache-ant-1.7.1/lib/ant-launcher.jar" "-Dant.home=${frameworkDir}/../../../../tools/ant/apache-ant-1.7.1" org.apache.tools.ant.launch.Launcher -f "C:/dev/doc/shared/Oxygen/dita/../../../main/core/build/build.xml" doc.syncall_nowebdev conditionally_build_doc "-Dwebhelp.trial.license=no" -Dsfdc.build.types=PDF

As you can see above, the ${frameworkDir} does not seem to have expanded. I used the entire path and it works fine. I verified that the path is correct for the ant jar above. 

Am I doing anything wrong here?

Thanks a bunch,

Nathan