Temp matters. I don't think you will find that snails are affected too much in the short run by changes in calcium or magnesium levels. Alk yes but if pH is close then it should be pretty fine.
The BEST way to acclimate virtually all snails is really a PITA:
Remove from the bag, and hold against the glass, above the water line with water just touching the bottom of the shell, until the snail grabs onto the glass. It will acclimate itself. This from Dr. Ron Shimek.
But doing this for an order of a dozen, not to mention several dozen, snails is just not realistic.
LFS do not get them in the wet paper towel. But hobbyists ordering from online sellers should demand they be shipped that way -- much less stressful on the animal, many fewer deaths in shipping, and better results in your tanks.
If a store puts your snails in water, at home I'd pour out almost all of the water, float the bag for temp, and then add the snails. I've never, ever had a problem adding snails this way -- trochus, pacific striped turbo, tongan nassarius, nassarius vibex, cerith, nerites, margaritas, and others. Astraeas, as I mentioned often sold as "turbos" and I am guessing what you are calling turbos, are dicey at best anyway and are best avoided altogether. No matter how you acclimate, they are likely to have 50% fatality rates at least within 6 months at most.
This info, by the way, is from personal experience, stories from countless other hobbyists, the most respected shops, and Dr. Ron's prolific writings.