Originally Posted by Katsunami
Still, I need to convert KF8 to epub before I can do anything with it in Sigil, or EpubMetaDataEditor,and I don't want that. I only buy books in my chosen base format, except when there is no other choice.
What you do is install the KindleUnpack plugin for Calibre. Use that to move the KF8 files to ePub (it does not do a conversion) and then you can edit/fix the errors in Sigil.
But if the KF8 has embedded fonts and you want to keep them, you have to Tweak eBook the KF8 and extract the fonts and put them in the ePub over the ones that are there. Also, you have to remove the file that says the fonts in the ePub are obfuscated.
But when done, you have an ePub that mirrors the KF8.