Make Image Assist work with Hierarchical Select (creation of new terms)

Background: Hierarchical Select lets users create new terms while adding a new node (that is optional - very useful). Ajax is used to achieve that. A tiny popup shows up, a new terms is entered, it is saved and selected afterwards. While this works at node/add/image it fails within image assist popup.

A Javascript message shows up: "Received an invalid response from the server."
followed by watchdog:

• warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'node_form' was given in /path_removed/drupal/includes/form.inc on line 366.
• warning: uasort() [function.uasort]: The argument should be an array in /path_removed/drupal/includes/common.inc on line 2843.

I think it is related to #455712: "Received an invalid response from the server." where Wim points out

This is not a bug. It's another module that does weird Forms API stuff and because of that, HS cannot retrieve the data is has stored that is necessary for the AJAX callbacks.

Could Image Assist be changed to work with Hierarchical Select?

cheers, Ronald