That looks sharp to me.
Maybe you expect them to be more crunchy and have very fine contrast, but that is ‘digital sharpness’, not what you would get from this.
Every DLSR picture you look at, has sharpening applied. In Lightroom / ACR even with the sliders to 0, there is still sharpening being applied.
What you are looking at here (Yes, even when ‘scanned’ through a digital camera) has no sharpening what so ever. If you want the same look, apply some (being subtle).
Don’t confuse detail for the sharpened look. Every scan of consumer 35mm film I took, if I compared them to a shot of a digital camera I took a few seconds later, I can see everything in the film scan that I can see in the digital picture. But that one single hair poking, it’s clearly there and visible in the film scan, but it really ‘jumps out at you’ in the digital picture. Because one pixel there is no hair, the next pixel there is hair, and the next pixel the hair is gone again… sort of like that :).
I guess in modern digital terms, a film scan is just really, really anti-aliased.
But if I look at that picture on your post, downscaled on my screen, I’m thinking ‘wow that is sharp’. I don’t see a problem with it.
That being said - what probably others have said - don’t expect the lenses from the olden days to be perfect, the focusing systems to be perfect, or ‘what looked like nicely in focus on a 4x6 print looks out of focus when pixel peeping in a 4000dpi scan’.
To me, pictures on films and scanned have detail but lack that pixel-crunchy punch. It’s recorded on film, not ‘sampled’ so to speak. And it’s one of the things I like about it. It makes things look a bit more ‘natural’.
But yes, I also have tried many, many sharpening plugins when I started film scanning. Somewhere along the line I just stopped.