Ive been doing that dance with the AvidMediaFiles folder for years even as far back as Meridien.
You would think by now they would have came up with a real solution.
To this day I am still in awe on why “professionals” upgrade to a new OS without a stress test.
I am still on Maverick for most of our Avid/FCPX setups.
Using Yosimete with Resolve.
Your system is almost close to my home back-up workstation that at times I lend to other Avid editors.
Only diff is I have more RAM and a Quadro 4000.
With an SAS and Decklink that old beast works with R3Ds easily.
But yes finishing is a different story.
Most editors dont finish on that one.