I agree with you Berserker, the 28x25 font is generally too big for most situation, although it comes from official Chinese SoD, and fits quite well specifically for places it's been used.

Can I ask if you have any idea how hzk files should be edited/made?

But I probably still need help from igrik. I mentioned that I tried to replace hzk24 with a duplicate of hzk12 in my post yesterday, and it did not end up well.
Support from WoG Native Dialogs seems to be required (or not?