Maybe dumb luck on my part, but my normal Lightroom/Photoshop adjustments seem to translate to Blurb's printing with fair accuracy. In the past, most of my editing was done on an old iMac (2011) that was calibrated only by software and by eye. (More recently, I've replaced that with a 2020 iMac, hardware calibrated with x-rite - but I haven't printed any books with the new kit to see if it makes any difference.)
The BookWright software does have a preferences box that allows you to enable/disable softproofing, as described <
here> but they don't go into much detail about what it does or how it works. I usually leave that enabled. Blurb also provides an ICC Profile that can be used for softproofing in Photoshop. More info <
here> Personally, I haven't bothered with softproofing my images in Photoshop. Most of my digital images are never opened in Photoshop, because Lightroom does almost everything I need to do. I believe I am above-average sensitive to subtle color shifts and I spend a fair amount of time getting the colors shadows and highlights on my screen the way I like them. Whatever I'm doing seems to work, because I have not noticed any significant color or dark/light issues in the printed books.
The BookWright software also has a checkbox to "Auto-enhance images added to project" which is described <
here>. The way I understand it, this is more for people who don't spend much time in postprocessing. I usually do not use Auto-enhance, but I did for one project. My wife's parents had a lot of old slides from when they were in the Peace Corps, and many were underexposed. I did the best I could with the scans in Photoshop, but many were still dark. Enabling Auto-enhance did brighten them up a little, but to my eye the colors got more saturation than I like. My Mother-in-law loved the book.
Obviously, it would be a good idea to print a small book as a test before ordering 40 copies!