I have 2 80mm Mamiya TLR lenses, one a black one purchased in 1980 (#915158) and the other an older chrome version made sometime earlier (#556454). My sense, when I used these two lenses was that the black one was "sharper" than the chrome.
I did a simple test. I printed this chart
on an 8.5x11 sheet of white bond and attached it to the wall of the house that was not in direct sunlight. I shot 6 exposures through the black lens, stepping through several f/stops, and then the chrome lens on the same 6 exposures, using Arista EDU ultra 100 film and developed it in Microdol-X. I examined the negatives, an enlarger print of each and several negative scans.
To be honest, I could not determine a difference in the resolution (where the lines in the image coverge on a central spot) - - both lenses could resolve the same distinction between the lines at the same points on the lines. So if by "sharp" we mean resolution, I could not find a difference. However, I could tell the difference between the lenses in the brightness of the white space between the lines and in the darkness of the lines - - what I would call the contrast or perhaps the dynamic range. The black lens had a crisper look (brighter whitespace, blacker lines) than the chrome lens did.
Was this scientific? Not really... but it helped me understand why I had the observations I did during actual picture making. So now I choose which lense to use based on the crispness I want in the picture... or whether I remembered to bring the other one with me...