welcome

the drum roll is perhaps the hardest thing for an electro kit to acheive well

I don't think the D4 is going to give the results you want

you need to look at the sample you are playing
and or
use multiple samples and change the dynamics of the hits and groove quantising ... a little random'ness could also help

not easy stuff

Using the piano-roll view (referred to as the Key Editor) in Cube you can just create your own drumrolls by assembling a midi sequence string made up of individual midi drum notes...you can add the notes one at a time (you'll need to have drum machine sounds assigned to the track you are using) in the "Key Editor" view, using the mouse.

A simple example would be maybe eight 32nd notes...once you determine the right note length and number (this would be dictated by the actual number of beats you want the roll to last, and the BPM of the song) you can then use Cube's midi "List Editor" to vary the midi velocity values of some of those notes to make the sequence sound more like a real drumroll.

You can also vary the note values within the sequence...like adding a 16th triplet at the beginnig or end of the sequence note string to make it sound less repetitious.

What makes a midi drumroll sound phoney is when all the individual hits within the roll are the exact same length and velocity.