I've never been very happy using my 90mm T-E on the CLE, as its 90 frames are pretty small. Better on the M2 and Z-I and Bessa-T. For 28mm lenses, I agree the CLE is best... at least among those I have. Including the R4a, and I say that because the R4's viewfinder is closer to the lens and is thus occluded more by the lens barrel.
The CLE and Z-I are least affected by lens intrusion into the viewfinder because the VF window is located off in the corner farther from the lens. But the CLE's lower viewfinder magnification makes its 28mm framelines more easily visible compared to the Zeiss-Ikon, and you can see more outside the lines.
So, in my view, the CLE is great with 28mm (and 40), the Zeiss-Ikon is excellent for 35 (and 50), the M2 is particularly good with 50mm (35 frames too close to the edges), and the R4 really needs tiny lenses to avoid seeing a lot of lens barrel and hood. So far it seems to be great with 25mm Skopar. I've got the 25 Biogon on the CLE now, with a CV 25 viewfinder on top for reference.
Man, what a cool versatile low-profile little camera that CLE is! Glad I just bought a second one after all these years with the first.