When we moved to 8.x, the entire tag system was refactored to make it more efficient. The only exception to this refactor was Vision Client Tags which fundamentally work exactly the way they did in 7.9. We have made adjustments to legacy scripting options (like readBlocking, delete, writeBlocking) to allow them to work, but the newer scripting options (configure, getConfiguration and even browse unfortunately) are a lot more problematic to implement because of the fundamental differences of how the tags are implemented.
The current behavior is expected. There are currently no plans to add additional functionality to be able to use scripting functions to configure Client tags.