Hey Jewellistic, sorry for the late reply, I had notifications disabled. I didn't end up getting it to work, I ran into some non-Hazel related export issues that led me to give up on trying to do things this way. I'm working on another way to do things, I'll let you know when I've made some headway.
As for other Hazel uses in a music production setting, there are a few things that I use it for quite a bit. One of the daily things is file renaming. I use Cubase with a large scoring template, and when I'm exporting stems from a cue I've got them all routed to group channels. I've named these tracks with a "==" at the end of the track name, so when I hit Export Audio Mixdown, I have a Metagrid Pro button triggering a Keyboard Maestro macro (I use all the automated help I can), it selects my export preset, and types == in the track search field, making it pretty effortless to just select the stem groups. This whole process saves 10-15 seconds, which isn't much, but ensures that I'm exporting the correct format, sample rate, bit depth, etc., and not making mistakes because I'm moving too quickly. The exported files have a "==" at the end of their filenames, but Hazel watches my project folder, and if a music file that's older than 5 minutes has a "==" at the end, it removes that, leaving me with clean filenames.
Hazel watches my Sequences folder and if it sees a new movie file (an exported score preview) or an audio file with Score Preview at the end, it'll copy them to a Dropbox folder that's shared with producers and directors.
In situations that I'm working with a collaborator (music editor, another composer, etc.) and want to be sending them stems, Hazel watches my project stems folder, if I put the stems from a new cue in there in a folder it will zip them, copy them to a shared Dropbox folder, and move the originals to a Sent folder.
If I'm finished a project, I've got a Metagrid/Keyboard Maestro macro that'll tag it "To Be Backed Up", which moves it to an external backup drive, sorts it into a monthly folder based on the date last modified, and removes the tag.
Then there's all the usual non-musical stuff, keeping invoices and receipts in order, downloads organized, and generally making sure that my computer is less cluttered than my brain. It's a pretty great system, not without its bugs and kinks, but it sure makes my life easier.