The two examples present in the question contradict each other.

For the first tree,

1
/ \
2 3
/ \
4 5

The traversal presented is is left to right on second level and right to left on third level, giving us [[1], [2, 3], [5, 4]

But for the second tree

4
/ \
3 12
/ \
8 14

The traversal presented is is right to left on second level and left to right on third level, giving us [[4], [12, 3], [8, 14]

So the traversal logic is different in both examples, and that's reflected even with the test cases present, especially the last one
tree5 which adheres to the first tree logic

Link to problem: Traverse In A Zig Zag.