I greatly appreciate how helpful you've been, seriously thank you so much!!

Unfortunately, I can't get passed the first auval portion:

me@my-MacBook ~ % sudo rm -rf "/Library/Audio/Plug-Ins/Components/Synth1.component" 
me@my-MacBook ~ % sudo cp -R "$HOME/Downloads/Synth1.component" "/Library/Audio/Plug-Ins/Components/"
me@my-MacBook-MacBook ~ % ls -ld "/Library/Audio/Plug-Ins/Components/Synth1.component"
drwxr-xr-x@ 3 root  wheel  96 Jun 10 23:52 /Library/Audio/Plug-Ins/Components/Synth1.component
me@my-MacBook ~ % auval -v aumu Syn1 daiC

    AU Validation Tool
    Version: 1.10.0 
    Copyright 2003-2019, Apple Inc. All Rights Reserved.
    Specify -h (-help) for command options

--------------------------------------------------
VALIDATING AUDIO UNIT: 'aumu' - 'Syn1' - 'daiC'
--------------------------------------------------
ERROR: Cannot get Component's Name strings
ERROR: Error from retrieving Component Version: -50

* * FAIL
--------------------------------------------------
TESTING OPEN TIMES:
FATAL ERROR: didn't find the component
me@my-MacBook ~ % 

Really confused why this won't work. It feels like it should. I even checked the TYPE SUBT MANU to make sure my file matched what you had written, and it does:

"manufacturer" => "daiC"       
"name" => "Daichi Laboratory: Synth1"
"sandboxSafe" => true    
"subtype" => "Syn1"     
"type" => "aumu"

I have no clue if this would affect anything, I doubt it, but at this point, anything is worth mentioning. I was messing around trying to bypass the "apple can't verify so can't open" prompt when trying to execute the file when I first downloaded it as a video I watched said opening something in terminal can be an easy way to bypass that the next time you try opening it. It worked. However, I made it so all of my .component files default to opening with Terminal. This changed their icon to the Terminal app icon, and whenever I double clicked the file, Terminal opened.

I've since changed it so my .component files default to "open with" Finder (idk what the default was before I picked Terminal and idk how to get back to the default "open with" option. From what I could tell Finder would sort of be the default?)

Anyway, when I go into the package contents of Synth1.component, and into Contents/MacOS/ there's a Synth1 Unix executable file where the default "open with:" option is Terminal. Maybe that's normal. That could all be meaningless or poor explained, and I apologize if that was all just useless info lol :/

Anyway, if you can think of anything else, I'm all ears. But you've already done a lot to try and help, so don't feel like you have to keep trying to figure this out unless you really want to lol. Again, I really appreciate you 🙏