There is a very rare and unusual problem where a user does an undo and it seems to skip back several undo steps.
This may be related to NOT quitting out of Screenwriter often enough.
This present version of Screenwriter is a 32-bit application, so it is subject to memory limitations that are much tighter than a 64-bit application. Normally, those limitations do not come into play.
We suspect there may be a small memory leak that over time puts pressure on the available memory space for the running application. If you regularly quit completely out of Screenwriter, we believe you will NOT see this issue anymore.
By "regularly quit out of Screenwriter" we mean: don't leave screenwriter running for several days. Quit out at least once per day.
Also, if you are getting LOW in your available disk space (on your boot drive), you MIGHT be getting into a "danger zone". You generally need at least 20-40GB of FREE SPACE on your hard disk, especially if you concurrently run other memory-intensive apps. MacOS needs available space to perform virtual memory operations, and running multiple simultaneous apps (or big apps, like photo or video editing) can temporarily eat up that space. Also, leaving lots of open tabs in Safari can cause low-memory conditions..
Restarting your Mac every so often (once per week) is also a good idea, not only because of Screenwriter, but to free up other large, hidden, temporary files.