This is a great follow up question! Unfortunately, nothing has changed with regard to the publicly documented API today.
However, there are some experimental features of the connectapi package that explore the possibilities associated with some of this functionality.
As it is still very much experimental, please let us know if you have any feedback associated with use cases this unlocks or additional improvements that can be made! We always love hearing from our users 
library(connectapi)
client <- connect()
my_app <- content_item(client, "myguid")
set_vanity_url(my_app, "/cole/test")
get_vanity_url(my_app)
?swap_vanity_url