Most unfortunately it got the rust one year after the sling. Many of the outer branches were infected. I contemplated to just throw it away. I tried all sorts of anti-fungus medicine although I knew that it was inpossible to cure. Anyway, yesterday Alex took off the wire, cleaned the tree and then we cut it back ruthlessly. Now we have some hope that we got all the rusty branches. It looks prominsing again.
I will now leave it alone for the summer and watch carefully next spring whether it has any rust. If not it will get some final styling. We'll see. Such is bonsai. A never ending story with ups and downs.