yast problems install xx and at the same time delete yy

Yast install rsyslog and yast want to delete systemd logging

if you select delete systemd … yast terminates
and as there is no log cant find what causes this

No. It wants to uninstall systemd-logger, which is just a compatibility package needed when no syslog daemon (rsyslog, syslog-ng, syslogd) is installed.

systemd’s journal will still be enabled after uninstalling that.

if you select delete systemd … yast terminates
and as there is no log cant find what causes this

Seems to be a general problem in Tumbleweed at the moment:
http://bugzilla.opensuse.org/show_bug.cgi?id=941870

Use zypper instead:

sudo zypper in rsyslog

Or the ncurses version of YaST should work as well:

sudo yast