This is message is for John and the community.
John, I got the impression that you were new to Windows. I wanted to bring to your attention the existence of
AutoHotKey. It's a free-software program to record and play back keyboard and mouse events. It's pretty advanced and I've seen some scripts do very complex things such as emulate a tiling window manager in Windows. I was thinking that it might help you automate the build process if it's very complicated.
For everyone else, I know that Sigil is very important to the workflow of many users and that high quality is a requirement. Maybe AutoHotKey can be used by the community to develop a suite of test scripts that can be run and test new releases for regressions. It comes with a script recorder that might be useful for recording actions for debugging. If you run into an error, replay the script to see if Sigil breaks again.