I understand that DFHack uses the happiness number, and Dwarf Therapist uses Stress value, but shouldn't these two lead to the same happiness category?
That is not the case - the Happiness number was removed when Stress was added, and the difference is entirely due to DFHack and Therapist using different labels for the different ranges.
If the happiness categories listed in the wiki to 0.34.x are still valid
Those categories are NOT valid anymore - you should be looking at the DF2014 page (i.e. the one for the current version), not one for an outdated version.
Thanks for explaining this. I was looking at the DF2014 Thought page, but I was expecting to find seven labels for the seven happiness levels displayed in DFHack's Happiness monitor at the bottom right. I only found them in the 0.34.x version of the article.
I'm starting to think that degrees of happiness are no longer what the thingy should show. Dwarves now have finely varied
Emotions which are somehow
color-coded. Maybe an indicator showing the population's current thoughts categorized by their color would be more useful.
In my last fortress, the monitor almost always showed me 90% of the fortress population in the top happiness category, the rest not too far below it. I was wondering what are they so ecstatic about, but when I looked in Dwarf Therapist or actually read dwarves' thoughts, I got a much more normal picture showing them just about fine, with the usual little annoyances.