Alphabets and Synesthesia
Studies show that the development of lanuages and pronunciation is heavily dependant on the geographical area they are being used. People living in rougher climates tend to develop accents or languages that are harsher where people living in milder conditions develop softer languages. This can be observed clearer in different areas of the same geography like different accents of a language.
We can see how the Bouba/Kiki effect works in sound-to-shape and shape-to-sound synesthesia clearly (with 90% consistency).
Kiki and Booba
“Ramachandran and Hubbard suggest that the kiki/bouba effect has implications for the evolution of language, because it suggests that the naming of objects is not completely arbitrary. The rounded shape may most commonly be named “bouba” because the mouth makes a more rounded shape to produce that sound while a more taut, angular mouth shape is needed to make the sound “kiki”. The sounds of a K are harder and more forceful than those of a B, as well. The presence of these “synesthesia-like mappings” suggest that this effect might be the neurological basis for sound symbolism, in which sounds are non-arbitrarily mapped to objects and events in the world.” (source)
So, we can assume that creating the glyphs and characters for alphabets people did map sounds-to-shapes. This would result in pointy “K”s and soft, fluffy “O”s.
In middle eastern and far eastern alphabets(Hebrew, Arabic) we see fluid usually single brushstrokes where in Cyrillic alphabet(s) we see seperate letters which are formed from lines mostly. Thus, we can assume that there is a direct relation to an alphabet with it’s origin’s geographical and climatic features.