I have noticed some issues regarding structure generation and through testing with the structure for tree generation.
This first issue is trees structures will generate in the water using structures. This would be a good feature to enable if the creator wishes to use this mechanic. However, it can look messy if you're not going for that look.
The other issue I have noticed is that trees still float from time to time, I know that I reported this but before but I did not know if you still are working on it or if its been thought to be fixed but I wanted to remind you that floating trees are a issue still :)
And lastly there is one last bug I noticed only on the 1.14.4 version that I can tell, if the block is on log rotation it sometimes rotates sideways in the structure. I am not sure if it does it with other rotation formats but it could be an issue across the board with the rotation feature.