Acceleration and jerk settings might be the fastest/easiest/cheapest fix right now (cheaper than buying a new table and faster than printing new parts!) I’m not super well versed with how to determine the best values outside of trial and error, so someone else might be able to step in and give more detail.
The basics, from what I get, is that by lowering the acceleration and jerk values, your machine won’t be speeding in to or out of direction changes. This causes less resonance through the machine, and therefore less ringing. Bracing your machine will help dampen the resonance, but changing acceleration and jerk should cut that raw amount down. I have Z-braces on my Monoprice Maker Select v2 and also tuned the acceleration/jerk settings on that and saw noticeable improvements from each one of those changes. Haven’t done it to my ender 3 pro yet.
e: to the point of the “STL file that can be printed reasonably quickly…”, sink the part you’re building in to the build plate to start printing just near the where it rings and see what happens. Or print the entire thing again after changes and compare apples to apples.