Most of the changes are in this commit
passthru("journalctl -u emonhub -n 30 --no-pager");
We just needed to add the www-data users to the systemd-journal group to allow it to read, this has been added to emonPi update and the emonhub config module readme
sudo usermod -a -G systemd-journal www-data
We still need to fix the log download button.