>Could it also be useful to have Cantonese pronunciation? Maybe for HK, but I don't
> know cantonese at all so I am inclined myself to stick with mandarin.

Just to interject here, I speak both Cantonese and Mandarin, and I
would say, that putting in Cantonese pronunciation is possible, but
not so practical. Mandarin is the official language of China, and it's
now becoming more and more necessary to communicate in Manadarin even
in HK. Mandarin has 4 tones, so it's much easier to deal with. Not so
with a Cantonese transliteration. There are something like 9 different
tones. And then there are different methods of transliteration - not
one, unified standard. So assuming you got the pronunciation correct,
you still have to get the tones correct too to make it work. So it's
much more difficult. It's a very ancient language, in many ways, quite
unlike Mandarin. But Mandarin is so much simpler and straight-forward.