I am missing the Japanese fonts HiraKakuProN-W6, HiraKakuPro-W6. I have used them extensively so it is really problematic to update every single artwork to a different (worse) font.
Searching the online Adobe font repository they are nowhere to be found.
Any help is much appreciated.
I can find no sign that these fonts were ever supplied by Adobe. [Note: many Japanese fonts may include Adobe-Japan6 in the font description, but confusingly that does not mean Adobe is connected to them]. What makes you feel they should be in the Adobe font repository?
Because I simply choose these fonts from within Illustrator. I guess they were system fonts. Adobe's font repository leaves much to ask for when it comes to Japanese fonts so I'll probably have to source them elsewhere.
They could have been system fonts, Adobe fonts, fonts included with any other app, or fonts downloaded (free or purchased). Illustrator shows all of them without favour.
I observe on https://support.apple.com/en-us/HT210192 that Mac OS includes Hiragino Maru Gothic Pro W4, not not W6.