At what point did you start training the trees to get that curve in the trunk?
I have 3 propagules in my sump that have just started to sprout roots and I plan to move them into a macro algae display tank once I have it up and running.
You have to start early. Roots come first. Once the tree has acclimated to the tank then you will see growth break out of the propagule top. The first several leaves will be tender. It is best not to stress them. At some point you will get a growth spurt where the "stem" grows fast, add wire and start then.
You will find the new growth trains well. Some of the best effects come from training the propagule, which will be your tree trunk after several years.