Adding Missing Chinese Characters to existing Japanese fonts

Hello!
I am exploring fonts for Chinese Traditional and found that actually google fonts for Japanese https://fonts.google.com/?subset=japanese are actually supporting many Chinese Traditional Wordings already.
If we would like to contribute, help to finish the missing characters, is it possible?
I think it includes several parts, the unicode itself, the glyph graphics/image. Some of them miss only glyph, some miss both.

Many thanks in advance.