~45 and ~35 respectively, using the default font of the game. That is, any more than that, and the text will go over the borders of the unit properties display, I don't think there is a real limit.
Not really why I'm posting here, though, I went back over the "original intended scale" argument I sort of got myself into with AlAmos a couple of days ago, and I realized that even with this more powerful editor, there's still hardcoded leftovers of the "battalion scale/150yards" that can't be adjusted. Namely, the artillery effectiveness modifier based on the number of men in the target hex -would it be possible to make that customizable, the same way as leader casualties and unit dissolution?
no truth - no justice
all false belief
blinded by morality
there shall be ... no peace