Sharpen Defocused Image (Deconvolution / Image Restoration)
You're after an algorithm in the family of "DeConvolution".
Specifically in your case, is called Blind Deconvolution.

Yet if you have some assumption the Blur you can use Wiener Filter or Lucy Richardson.
Both of them are actually the MMSE Estimator just with different assumption of the noise.
Both of the methods are actually "Inverse Filter" on an Low Pass Filter, which means they are High Pass Filter, just like the Unsharp Filter you applied.
The difference is those methods are optimal per given "Blur Model".

Yet, if you go after the Blind Deconvolution, today the best estimators are based on some prior of the image.
Something like the distribution of the Gradient of the image and stuff like that.

Yet if you are only after the text in the image.
Something simple like Wiener Filter + Edge Detection should do the work to give you most data.