Imported instance children arrive with componentId null, so every component edit re-cloned them and compounded per keystroke into runaway memory. Also fixes sibling inversion, extras jumping to front on sync, and stack overflow on self-referential components.
Sync: match unmatched children by name+type forward instead of cloning, guard self/cyclic sync via isDescendant, and keep unmapped extras at the end.
Import and paste: link children positionally at import time so renamed children stay linked. Clipboard paste is scoped to new instances only so existing instances are untouched.
