When updating many packages (e.g. libreoffice, kernel, etc.), I noticed that
the "posttrans" display displayed progress for libreoffice icons up to 60%,
then got stuck, and it was the last posttrans indicator seen. However from the
noises of my disks I noticed that the kernel also had triggered rebuilding the
initrd and reinstalling GRUB2.

>From that I conclude that the posttrans progress display is broken.

I also searched y2log fro "posttrans:" messages, confirming my point of view:
2019-10-07 09:39:12 <1> pc(4931) [zypp::posttrans]
RpmPostTransCollector.cc(collectScriptFromPackage):77 COLLECT posttrans:
/var/adm/update-scripts/posttransl4NIpO/libreoffice-icon-themes-6.2.7.1-lp151.3.6.1.noarch.rpmLnrBBe{-
0700 0/0 size 254}
2019-10-07 09:40:56 <1> pc(4931) [zypp::posttrans]
RpmPostTransCollector.cc(collectScriptFromPackage):77 COLLECT posttrans:
/var/adm/update-scripts/posttransl4NIpO/ibus-1.5.19-lp151.2.3.1.x86_64.rpmysd9Ev{-
0700 0/0 size 24}
2019-10-07 09:41:22 <1> pc(4931) [zypp::posttrans]
RpmPostTransCollector.cc(collectScriptFromPackage):77 COLLECT posttrans:
/var/adm/update-scripts/posttransl4NIpO/libreoffice-l10n-en-6.2.7.1-lp151.3.6.1.noarch.rpmlRMsQg{-
0700 0/0 size 238}
2019-10-07 09:42:23 <1> pc(4931) [zypp::posttrans]
RpmPostTransCollector.cc(collectScriptFromPackage):77 COLLECT posttrans:
/var/adm/update-scripts/posttransl4NIpO/device-mapper-1.02.149-lp151.4.3.1.x86_64.rpm7jPj3s{-
0700 0/0 size 167}
2019-10-07 09:42:39 <1> pcrz00066(4931) [zypp::posttrans]
RpmPostTransCollector.cc(collectScriptFromPackage):77 COLLECT posttrans:
/var/adm/update-scripts/posttransl4NIpO/lvm2-2.02.180-lp151.4.3.1.x86_64.rpmH4FrlA{-
0700 0/0 size 167}
[...then the scripts are executed...]
device-mapper calls dracut to rebuild the initrd
All the scripts were actually executed, but not displayed

2019-10-07 09:45:53 <2> pc(4931) [PLUGIN] PluginScript.cc(~PluginDumpStderr):75
! INFO:root:COMMITEND