There’s not much that can be done to improve training.
For a start the instrument rating test and subsequent renewals for airline crews should be 50 percent automatics and 50 percent manual raw data flying. That means no flight director and no autopilot on instrument approaches.
That change alone will force managements to think twice when pilots inevitably fail to keep within instrument rating tolerances during manual instrument flying. Only then will pure instrument flying skills gradually improve. After all, isn't that what we are trying to achieve?