the "weird" font, is the games default font. The nice looking font, is the TrueType font. Default font is hard coded to use certain letters as sprites. Default ascii graphics, a 0 is used as a coffin. Alot of the different graphics packs out there change most of those characters to look like what the sprite is supposed to be. Hence, the 0 turns into a tiny coffin with a cross on it, to draw your attention "Hey, look at me! I am somebodies grave!"
The problem is, alot of the dfhack plugins that add extra GUI stuff, like workflow, and the built in version of Therapist, etc, DONT use truetype.
Does that make sense? I hope it does, because im half asleep atm.