>>42
差分は JavaScript を使うのが簡単なので，下記のような Task を組めばよい．
なお，オリジナルフォルダーかバックアップフォルダーのどちらかが空のときは自明なので処理は省いてある．

A1: List Files [ Dir:original Match: Include Hidden Files:Off Use Root:Off Sort Select:Alphabetic Variable:%original ]
A2: List Files [ Dir:backup Match: Include Hidden Files:Off Use Root:Off Sort Select:Alphabetic Variable:%backup ]
A3: If [ %original1 Set & %backup1 Set ]
A4: JavaScriptlet [ Code:originalNames = original.map(x => x.replace(/.*\//, ''));
backupNames = backup.map(x => x.replace(/.*\//, ''));
var diff = originalNames.filter(x => !backupNames.includes(x)).toString(); Libraries: Auto Exit:On Timeout (Seconds):45 ]
A5: If [ %diff neq \%diff ]
A6: Variable Split [ Name:%diff Splitter:, Delete Base:On ]
A7: Flash [ Text:%diff() Long:On ]
A8: End If
A9: End If