I think one of the Timothy Zahn Star Wars novels attempted to spackle over that faux pas. Something about the Falcon being fast enough to allow its pilot to fly a shorter course around a gravity well.
That was “I, Jedi” I believe: Idea is - as you summarized - that Kessel was in the midst of the Maw cluster of black holes. The faster the spaceship, the “straighter” that it could fly through the winding path going between the black holes. Thus, an average ship might need a path 60 parsecs long. A faster ship can get through with a shorter path - 50 parsecs long. A very, very fast ship then only needs the 30 parsec length.
Kind of like a teenage driver claiming his “time” in a 1/4 mile rather than the speed. Or a claim for 0-60 in ___ seconds, rather than an actual acceleration. A football player talkin’ about his time in the 40 yard dash.
Not quite. It was considered impossible to get through The Maw (nice, I'd forgotten the name), but when they did get through thanks to the help of the powerful Force-sensitive (later Dark Jedi, then Jedi) Kyp Durron (no, I didn't have to look that one up), Han Solo and his fellow travelers (don't remember who...Lando and Chewbacca, maybe?) stumbled onto the secret Imperial research facility in the center where the super-smart scientists had developed the Death Star and the Sun Crusher. The security force was commanded by Admiral Daala, I think. That chick was hard core crazy.
It was definitely the Jedi Academy series, though I haven't read "I, Jedi" so I couldn't confirm or deny if Kessel or The Maw play a part in it.