I propose that this sort of font be called "decipherable" rather than "readable".
I could learn to read this. I can kinda-sorta make out the example, because I already know the Declaration of Independence. Is it readable the way, say, this text is? Or the PICO-8 font? No.
Many people's handwriting is best described as "decipherable" as well, yes.
A readable font takes no practice to read, presuming you already read the script of the font and the language of the text. A decipherable one can be sort of limped through at first and probably picked up to fluency with experience. Although, as the article notes, this font has homonymous glyphs, there are only a few words where that creates ambiguity, and as few as none where it would be ambiguous in context.
No. Any font takes a lot of practice to read. Maybe the difference is that you define "readable" as readable immediately by anyone who is already familiar with modern fonts?
I'm sure medieval fonts were readable to pepole who wrote them, but when I look at them I need to labor at every letter.
if more than one bit of color was allowed you could make different levels of grey/opacity hint at where the opening in the symbol should be. just as learnable and now it's unique.
taken to a silly extreme, you could compress 26 letters into 2 pixels, 3 colors, and 3 levels of opacity. before even considering a time-dimension.
I could learn to read this. I can kinda-sorta make out the example, because I already know the Declaration of Independence. Is it readable the way, say, this text is? Or the PICO-8 font? No.