@Hin-Tak Leung I think maybe you can try to compare bitmaps to find out the detailed difference between rasterizers, or maybe write some special fonts to "stress test" them. (Pomax on Github has made some special CFF OTFs that contain unusual opcodes which crash many font editors and rasterizers. What may be a good sample for you.)
@Mike Duggan @Hin-Tak Leung I tried to make a series of previews about how bad the status quo, current gridfit included in Microsoft YaHei is, compared to sfdhanautohint.. The sample text is “我能吞下玻璃而不伤身体 東国三力今書鷹酬鬱愛袋永”. You can see the serious stroke stacking in character "鷹", height inconsitency (書), and many distortions in the Bold variant.
DirectWrite under Chrome:
DirectWrite under Edge (DW with less AA levels, Ah, that's another problem: the DW in UWP requires more AA levels):
Recalculate a set of GDI-quality gridfit for Microsoft YaHei, DengXian, Microsoft JhengHei, Meiryo, Yu Mincho, Yu Gothic and Malgun Gothic using some fully-automatic process (machine-learning/AI powered?) by the Typography team/OSG/MSR. The current one is unacceptable, especially in Microsoft YaHei. (Maybe you can reference my sfdhanautohint.) All weights. All characters. Or...
Enable vertical antialiasing in GDI and disable gridfit in the fonts I mentioned. Or...
Completely remake a set of pan-CJK typefaces for Windows, just like how Apple and Adobe did.
ps. I tried to rehint Microsoft YaHei using sfdhanauothint, the result looks good to me but is still not perfect.