Maximum regen rate?

The DIC number is the total high voltage power of the system - if it's positive, power is being pulled from the battery (or engine)
If it's negative, that amount of power is being fed into the battery.

When braking or L-coasting to a stop, the rate of regen is proportionate to speed/rate of deceleration. If you're not going fast enough, you might not see that max number.

If you are driving in single motor mode, you will see maximum 55kW regen from the single large motor (half the max output)
If you were in dual motor mode, you might see up to 60kW regen as both motors work together. This isn't as common as the system usually declutches fairly quickly. Typically 55kW is max.

Shifting to L at that speed may get you there, but might be a bit below.
L+moderate to firm brake pressure certainly would.
But as you slow down, the regen rate will drop proportionately. So you'll only see 55/60kW max at the very start of the deceleration.