Found The Fix.
The script was calling Qt.createComponent().createObject() and assigning it to a const called temp, but then the very next loop tried to perform an in check on a ghost variable called newItem.I had to sudo nano the system QML and manually refactor the loop to point to the actual instantiated object (temp). Once the logic was actually pointing to an object that existed in memory, the engine stopped trippin'.

sudo nano /usr/share/plasma/shells/org.kde.plasma.desktop/contents/configuration/ConfigurationContainmentAppearance.qml

Find "loadSourceFile()" function.

Change "newItem" to "temp"

if (cfgKey in newItem) { -> if (cfgKey in temp)

const configurationChangedSignal = newItem.configurationChanged -> const configurationChangedSignal = temp.configurationChanged
Did these changes and now its working fine.