To address the second question, there are several reasons.
A general reluctance to publish data exceeding SAAMI pressures.
A lack of concenus as to just how warm Warm Loads should be. Some of the Elmer Keith .44spl loads were seriously hot.
leads us to ; There is ample historical data from Keith, Skelton, et al. I'm too Luddite to link, but Brian Pearce has written up .44Spl (.45Colt) loads at various pressure levels with both classic & modern powders.
There are actually few (production numbers) revolvers "needing" warm .44Spl loads, ie actual .44spl chambered revolvers of suitable strength, that their owners are willing to use warm loads in. Early N frames, Colt New Service, 1st gen SAA are now valuable enough few owners care to shoot warm loads in them. There are only so many '80s vintage N Frames, Freedom Arms M97 , and large frame Blackhawk conversions in circulation. 50th aniv frame Blackhawks, and certain of the better SAA clones are believed by some to be suitable for semi-warm loads.
All that said , the closest to a concensus loading is the "Skeeter Load" aka "Elmer Keith's Light Load", to wit 7.5gr Unique with 240-255gr cast SWC, giving 850-1000fps depending on individual gun & bbl length.