HDR does not look good
I have now realized that what I was seeing was the typical halo effect of high sharpenss. The image examples in this article illustrates the effect perfectly.

Decreasing the sharpness from 10 (max, the default) to 1 (lowest) improved the fonts immensely. Even 5 is pretty good, but as far as I understand it sounds from forums like the lowest setting is most faithful to what the OS wants to display.