Well, using the A7R II it's even harder for the lenses. To some degree I can confirm what you are saying.
The 25mm (which is actual more like 26) is one of the weakest lenses ion the whole Contax C/Y line, having soft corners WO. But it still has the Zeiss magic when stopped down to around 8 and it flares beautifully.
The 18mm is slow and has softer corners too, but gets pretty good when stopped down only one step. It's strength is a very nice way of correcting distortion for a lens of the era when there was no in-camera or software correction. But such a wide FF lens was a hard earned compromise at the time, so if you want ultimate sharpness and no CA at all, it's easier to do for current lenses where the manufacturer just doesn't care about distortion and leaves it to the camera.
Zeiss did it perfectly right for the 21mm, but that is too expensive now.
If you don't like the 35mm f2.8, have a look at the 35mm f1.4. It's big, heavy and expensive, but marvellous.
I did like the 18, even with its weaknesses, but eventually I sold it because I seem to see the world either at 15 o 21mm, but not at any intermediate focal lenght...and every time I buy an intermediate focal lenght I end up selling it. Then I decide to try again a few years later, but it ends just the same.
Last year I found a 35/1.4 for 300€, from a reputable shop, and foolishly waited too long (couple minutes!) to place the order. Needless to say someone else snatched it. At some point I'll buy one, but not at current prices.
Btw, the 35/2.8 (like almost all my Contax lenses, bar the 18 that is fairly soft on that sensor) performs great on the Fuji x-trans!
And on a side note, the humble 50/1.7 (or at least my copy) is so sharp on the A7r that it looks like you stepped up one format...