Hmmm... So the article seems to suggest that for every insertion of a character, a log time lookup is made. Is that really the case? If so, why is the leaf node

Hmmm... So the article seems to suggest that for every insertion of a character, a log time lookup is made. Is that really the case? If so, why is the leaf node that the cursor is in not saved? If you were to use a B+-tree implementation then you would already have access to neighbour pointers for rebalancing purposes, making the majority of incremental changes very cheap (constant time). This is just a thought, there may be good reasons why it's not possible.