Why-when, selecting a symbol, on the Zhuyin keyboard-area, many characters show, with that symbol, but, only a few, with the particular, Zhuyin symbol, show on the search results?
Our Zhuyin search method doesn't do prefix matching very well at the moment - it will only generally accept an exact input, when a Zhuyin keyboard might accept the first character of a two-character syllable or the first one or two characters of a three-character one.
The 'I' is another way of writing the Zhuyin 一 character - this is a font-specific variation and it seems like this particular font does it that way.