To answer this question, you need to look at ballistics of original loads and those of today.
There is a Ballistics Chart for Revolvers in the 1925 S&W Catalog.
32 S&W, 85 grain bullet, velocities were 664 fps
Muzzle energy of 83.5 foot pounds
38 S&W, 145 grain bullet, velocities were 670 fps
Muzzle energy of 147 foot pounds
Barnes book on Cartridges of the World lists the following standard factory loads:
32 S&W, 85 grain bullet, velocities were 705 fps
Muzzle energy of 97 foot pounds
38 S&W, 145 grain bullet, velocities were 630 fps
Muzzle energy of 176 foot pounds
The 32 S&W and 38 S&W were introduced in 1877-1878 when black powder loads were standard. I can not find any references to black powder velocities or ME, but would guess that they are similar to early smokeless loads.
I do not have any knowledge or references that new factory ammo is loaded lighter than original, but would say the it is likely the velocities of these calibers have remained pretty much the same over the last almost 150 years.