Does anyone know the developmental history of the taleth qetanah ('arba qanfoth), or at the very least, know of something in English, Ladino, Portuguese, or Spanish which outlines it?

I can tell you that I've only ever heard it referred to as a "טלית קטן", not a "טלית קטנה".

mosheshmeal
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Wikipedia has something, for what it's worth. And it mentions that it is also called a talleth ketanah, btw... I never heard it called that before, but there it is...

According to Sephardic diqdouq, the word "taleth" is feminine, hence the plural "taletoth" and the terms "taleth gedolah" and "taleth qetanah." As for information, I have already read the Wikipedia entry, and was hoping for something more substantial.

It certainly makes more sense, from the point of view of dikduk, to say talis gdolah, talis ktanah and talisos; common Ashkenazi usage treats "tallis" as masculine, hence talis godol, talis koton and taleisim. Modern Israeli 
Hebrew combines both usages idoesyncratically, since they use talit gadol, talit katan and talitot.