I'll try your modified version later. Your screenshot looks much different than what I saw. There weren't any Lua errors, though, and it seems like there should have been if the patch wasn't fully applied.
Aye, that's a tree-in-tab-in-tree(leaf), which is possible with current syntax. What's not (yet) allowed is tree-in-tree(leaf) without the intervening tab, which I think Phanx was aiming for, or anything-in-tree(nonleaf), which I would find very useful.