Calling on gedolim to apologize for shfichus domim and chillul Hashem is a very strong claim. You'd need either a daas Torah to publicly say it, or extremely strong proof, or possibly something else.
Their signature was affixed to a proclamation calling a chashiva talmid chacham and ירא שמים a maskil etc. As per Rav Aaron Feldman and the Badatz who’ve been intimately involved for years this is pure libel.
What proof are you asking for, that their signatures appeared, that that disgusting slanderous claim isn’t true, that the libel is affecting that תלמיד חכם, that they have not clarified, as Rabbi Feldman did, that they didn’t sign that kol koreh?
Let me know, happy to provide.