
to (calibre editor) displaying embedded fonts.
IMHO Both editors share a few of the same display quirks (because they use some of the same code libraries). But I get the feeling that Calibre has a few less.
I am liking Calibre's equivalent of Flightcrew over Sigil's.
My jury is still out

on the TOC generator.
Remember, the 'Editor' is not done, whereas Sigil development is known to be stalled.