Icons that are missing in other languages were likely caused by translators accidentally translating icon IDs. If you spot them, please delete the translation.
Here's an example of a string:
Surprisingly, I can't seem to find the translations of this project either. Maybe @vkareh knows?
The deadline for 20.04 translations is April 9th, according to the release schedule. They might be synchronised before this date. It could take some time for packages to update.
Ubuntu flavours share the same package (ubiquity-slideshow-ubuntu). Right now, the last update was 5th March 2020. See details on Launchpad for the Focal Fossa series.
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