Greetings,
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I have modified fedora-live-kde.ks by adding live user in its post section: https://pastebin.com/raw/CQVkPr8S
This is my flattened kickstart: ksflatten -c fedora-live-kde.ks -o kde_flattened.ks -v F33 https://pastebin.com/raw/B5Ph4Rbw
I built an iso using livecd-creator with your kickstart file... and I believe I discovered the root cause of your problem (no liveuser on the media)... and that is, with the package set you have provided, for whatever reason, the shadow-utils packages (which provides useradd/adduser) isn't part of the package transaction and as result the post section where the user gets created can't find the command and can't make the user. Just added that package to the list and at least that part should be resolved.
TYL,