I would say that if you are on final and the EDM is flashing then all you can do is ignore it. You've got to land somehow...
The EDM is looking for a specific CHT drop rate. It doesn't care whether you are dropping from 450F to 400F, or from 350F to 300F. But in terms of structural strength of aluminium there is a big difference between those two.
As to how one can manage the engine, that's a separate issue.
One can enrich the mixture gradually before the anticipated descent, to cool the engine, and when you start the plummet you reduce power (to avoid busting Vne, to stay below Va if in IMC, whatever) and lean to peak EGT and that reduces the cooling rate.
Or one can just think ahead and reduce power before the descent to say 18"; after a couple of minutes that gives you a low enough CHT to not worry, and you can descend at that power setting, gradually reducing power further as you go down, 1" of MP every 20 secs or so.
You can play with this next time you go up. It's quite easy - I rarely get the warnings myself. Just thinking ahead and reducing power nice and slow will do the job.
Lycoming may have data on all this but if they have (unlikely) they won't be revealing it because this whole business is wrapped up in liability and litigation. Loads of people get cracked cylinders, in many cases for no apparent reason (not stupid pilots, know about engine management, etc) and loads of them now have EDMs and keep the data all the way back. Lyco can and do wash their hands of warranty as things stand but could easily make a rod for their own back by coming out with clear guidelines, because many people could prove they never exceeded them. Also if they came out with anything, people would force them to reveal when this data was discovered and why didn't it come out earlier, etc etc. Lycoming do get sued very frequently, and if you actually take legal action they do settle fast (I've known people who got whole new engines, and even on SB569 people have got Lyco to pay for engine removal) but they get you to sign an NDA so you can't talk about it. This is how things are done in aviation - you stonewall and whitewash, and then settle fast if the punter does what he threatens (most don't).