)Given my understanding of how the velocity drops stack from the Effective Speed by Hyper Band table to carry about 500 KPS over the wall you'd have to start your drop to n-space from no higher than the Gamma bands - which seems unusually low for warships.“Tracking’s just picked up a group hyper footprint. CIC makes it thirteen point sources. They’re almost directly astern of us at six-point-eight light-minutes and they brought about five hundred KPS over the wall with them.”
Specifically if you're cruising at their top speed, 0.6c (179,875 KPS) and drop from Gamma to Beta you lose 78% of your velocity, drop from Beta to Alpha and lose another 85%, drop from Alpha to n-space and lose a final 98% of your velocity. 179,875 * 0.08 * 0.15 * 0.22 = 474.8 KPS.
There's no particular reason Scotty's ship couldn't have been cruising in the Gamma bands (maybe there were rouge waves higher up). Alternatively they could have paused their descent in the Gamma or lower bands and built up enough velocity to drop into n-space with 500 KPS if that's what Scotty desired. But doing a continuous drop from no higher than the Gamma bands does seem a somewhat unusual choice.
If they'd dropped straight from the Theta bands their max velocity across the wall would have been a mere 3.7 KPS!. OTOH if they'd wanted to carry as much velocity as possible they'd have worked up to 0.6c in the Alpha bands and would have carried 14,390 KPS across the wall. Instead they opted to carry just over a third of that. <shrug>