I diffed the Debian and Ubuntu build logs, and the only difference I see in build flags is that Ubuntu adds the -Bsymbolic_functions link flag. Though, if I correctly understand the description of the flag, then I don't think that's related.
As for package version differences, the only signficiant dependency at runtime (other than libc6/libstdc++) is libicu, but the package verison in Debian and Ubuntu is identical. What I'd really like to get is a stack trace of one of the exceptions thrown by the sample programs. A core file would be even better. But I don't have access to an s390x system. Would someone be willing to sponsor my temporary access to the s390x porter box? If not, could someone with access get me a stack trace or core file showing the failure? I could provide instructions if needed.
