The analysts' assessment of this missile is probably accurate.  This wasn't "maybe", but clearly, a lofted trajectory.  A more typical flight path (typical for a military missile, that is) would be much flatter and yield a longer range.

But if this is a liquid-fueled design, there's still a big question about reliability.  Their recent track record with those is none too good, and building reliable liquid-fueled missiles is a non-trivial task.

What I find extremely doubtful is KJU's claim that it can deliver a "heavy" nuclear warhead.  That's pure brag, since SK doesn't have the capability to build ICBM-style nuclear warheads.  They're back in the late '40s / early '50s in terms of their bomb fabrication.  They may have access to more recent designs, but are incapable of actually constructing them.