I use PHPStorm and its Toolbox app to download updates. Each time there is an update, it puts a new version of the application in ~/Library/Application Support/JetBrains/Toolbox/apps/PhpStorm/ch-0/[version number], Eventually it deletes the old version.
So as soon as a new version of PHPStorm installs, the path in a "Specific App Did Activate" trigger is no longer correct. It would be easier if this feature worked with the application's name or ID rather than its full path.
After I started writing this, I figured out how to do what I wanted with a Conditional Activation Group. But, wow, that's a lot harder to set up.