You mention that one might link 'm' to 'Green', for arbitrary reasons. Makes me wonder if anyone has tried actually colourising the typography. If every instance of 'm' was tinted green, every 'p' was tinted red, and perhaps a rainbow of tints for the most problematic characters, might the colour patterns made with words assist the reading process?
Speech language therapists ("orthophonistes" in France) actually use that kind of technique as training. Sometimes it's colors, or it can be pictures or symbols right above or below letters or words.
