Have you looked at StitchBuddy's Automator actions? There is an action to create a PDF, and you can easily compose a workflow which is asking for Finder items and generating catalog PDFs.
Here is a video tutorial illustrating these steps, creating a combined (master) catalog PDF, with some additional information about file size optimization. It doesn't walk recursively through subfolders, but you might want to look at Apple's Automator action "Get Folder Contents" to achieve the very same. BTW, I'm confident you are aware that StitchBuddy cannot read .HUS files…
So no need to spend additional money if you're willing to give Automator a chance … piece of cake for someone considering Python for the job 😉
Maybe you'd like to leave some feedback how it worked out, and I'm appreciating fair app ratings and reviews in Apple's App Store…