What feature do you want to see added?

The generate tree brush works but the leaves are falling of when the randomtickspeed of the server is not 0, so it would be nice if the generated tree don't lose its leaves after placing.

Are there any alternatives?

You could set the randomtickspeed to 0 or use a noblockphysics plugin but you can't do it in some cases for a long time as it breaks vanilla behaviour of plants.

Anything else?

Just a picture what happens if you don't know that it happens for visualisation purposes