Some time ago the YaST team started to get bug reports about the "System Log" option displaying no content. By default this component opens
/var/log/messages and after the switch to systemd that file is not longer used by default. Thus, we created the yast2-journal module to allow viewing of the systemd journal (journald). But the new module did not substitute the old viewer because the old one is still useful to inspect plain text files like
/var/log/boot.log and because is still called from other YaST modules.
The current situation is confusing. In the YaST main screen we have now "System Log" and "Systemd Journal". Is not unlikely that in some other places we only have a reference to the old one. It's not clear when to use which one. That has been reported several times, like in bug#948729.
On the other hand, some of the YaST modules calling to the old dialog should be changed to start calling the new journald-based one, like reported in bug#1008493 about yast2-tftp-server. That would need some small improvements in yast2-journal, that is not reusable enough (nothing big or difficult, but it needs to be done).
So the idea is to dedicate one day to fix the log viewers mess in YaST.
This project is one of its kind!