Tests done in one sandbox (AWS instance with Windows 2022; security protection disabled).
Events generated with use of mimikatz, where local user was running the tool.
I was getting '<Data Name='SourceUser'>NT AUTHORITY\SYSTEM</Data><Data Name='TargetUser'>IP-0ACA0544\localuser</Data>' in most cases and '<Data Name='SourceUser'>IP-0ACA0544\localuser</Data><Data Name='TargetUser'>NT AUTHORITY\SYSTEM</Data>' in few cases.
Tests done in another sandbox were showing localuser as a TargetUser till first restart of machine and then it was as expected.
I think that can be also observed here: https://github.com/OTRF/OSSEM-DD/issues/26 (vs https://blog.menasec.net/2021/12/detecting-token-stealing-using-sysmon.html )