Securing wiring around the electrical panel - NEC 2017 appropriate?
Killing two birds with one stone
Dealing with attaching the green and yellow cables to the backboard is simpler than it looks, using stackable MC straps such as the Arlington NM310.  Note that the NM310 fastens using a screw instead of being driven in directly or nailed to the surface it's attached to.
And yes, you do need a staple or strap for that SE cable
You do, however, need a staple or stap for the SE Style U cable to meet NEC 230.51(A) securement requirements (aka within 12&quot; of the box).  Problem is, generic SE Style U straps and staples are designed to secure the cable flat to a surface, and the 90° twist required to do that in your case makes securing the cable flat to the backerboard impractical without excessively twisting/straining the cable.  One could try using a SE Style R staple to attach the cable to the backerboard instead, but sizing may be an issue with that approach.