Is it possible to have the Task Dialog interface in OpenRoads Designer similar to how it looked in SS4?
No. The civil CONNECT products utilize a Ribbon interface to hold the commands. There is not a way to configure it back to a Task Dialog. The CONNECT products also offers a Search bar in the upper right to aid users in finding specific tools. For example, below the word Terrain is searched and all the commands related to Terrains appear. Each command lists the different locations where you can find this tool. You can click on the tool within the Search to activate it OR browse to the location provided under the command to better learn exactly where everything is.
For more information, see this wiki: https://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki/33789/equivalence-video-interface-difference-between-openroads-and-openroads-designer.