No discussion appeared on fedora-devel, but it seems that the size increase from F28 has been taken care of in the updated proposal.

+1

@kkofler any comments?

This is better than before, but the total size (and thus, the size of the default install) is still increasing by 26%. For those needing only one language, the unification even makes things worse (the worst for Japanese where we see a factor 74 size increase). I am also still not convinced that using up 200-300 MiB of live image size to cover just 4 languages is worthwhile (i.e., IMHO, the fonts were already too large in F28 and earlier).

I don't think the unification makes things worse. "This is better than before" as you said comes from the efforts of this unification right. as those three languages have a lot of common glyphs in Unicode, the unification makes more sense to compress the size.

Needing more sizes than Latin is inevitable because the amount of glyph coverage is hugely different. I think most huge specification may be GB18030 for Chinese though, they have 27533 characters as must and 42711 characters as optional.
This isn't uselessly large, but necessarily large. there are nothing we can do at this point as long as we support those languages.

But those sizes do look unreasonably large when we see how the (unfortunately no longer maintained) WQY MicroHei font was able to cover ~40000 characters in only 5 MiB.

VL Gothic was also quite small, how many characters does that include? (I suppose Japanese Kanji are fewer than the ones used in Chinese?)

Why are the Noto fonts so much larger?

This isn't that easily comparable because both format is different. WQY MicroHei fonts are stored in TrueType format which uses quadratic Bézier curves (as well as VL Gothic) but Noto CJK are stored in OpenType/CFF format which uses cubic Bézier curves. plus, coverage is quite different. MicroHei has 49531 glyphs in the table but Noto CJK has 113310 glyphs. this may be the reason that mostly makes that diffrenent in the size.
Other than that, even though some tables can be unidifed, some tables can't be. this is because Noto CJK isn't necessarily rendered same for CJK. it has the uncommon data for them as substitute.

MicroHei is designed for embedded device, the size is small.

But the quality of MicroHei is not as good as Noto or Adobe Source fonts.

+1 here.

While I recognize the issues related to size increase, I'm going to go ahead and vote +1 for this. I believe the benefits outweigh the negatives.

+1

1 week has passed and I count the votes as +4/-0. I will mark this change as accepted.

+1 from me too. Approved (+5, 0, -0)

Announced today.