I only stumbled across this thread quite late in the day, buried away in "ante toki"! I've been working in a similar vein, but with a twist.. I'm also mapping Toki Pona words to Chinese characters, but I'm then using that Unicode mapping as a basis for a purely Toki Pona script / font.
jan Mato pointed me here: I did a quick comparison of jan Josan's list and there's approx 50% agreement in our mappings (much less with jan Jopi's list because I was using Chinese rather than Japanese meanings as a basis for the mapping).
The mapping process isn't easy hey? There are so many characters to choose from with very subtle shades of meaning, not all of which correspond neatly to the TP words. I must admit, I didn't spend too long agonising over my choices since I was more interested in creating the font for the new script.
Anyway, I've summarised my work so far on this website: http://mike.oconnor.net.au/tp
Mike / jan Majika