the new harftex has no fontloader library anymore
Probably the fontloader library will come back (or even is already back). But it would be nice if you could comment. e.g. at the harftex github, if you actually need it.
LuaTeX-ja uses the fontloader library for getting font informations:
But the code is old and not reviewed. So I will look into whether the fontloader library is not needed anymore (but not at an early date).
So I will look into whether the fontloader library is not needed
I removed the use of fontloader in the development code (kitagawa_test branch). (The issue will be open until release of the new version of LuaTeX-ja.)
The issue will be open until release of the new version of LuaTeX-ja.
I uploaded the new version to CTAN.
This is not a bug report only a notification about current developments which could affect luatex-ja. harftex (a luatex with harfbuzz included, https://tex.stackexchange.com/a/493185/2388) has dropped the fontloader library. This means that luatex-ja doesn't work with this luatex-variant anymore. https://github.com/khaledhosny/harftex/issues/6.
The author of luatex is also considering to drop the library in texlive 2020. Ulrike Fischer