Errors when making cut out holes on PCB for SMD Leds

I’m trying to do the same as this Hole for component - #4 by 636Steve cutting out a square hole on the PCB so I cant fit one smd SK6812 MINI-E led behind the PCB for each cherry keys on a micropad.
I modified the SK6812 MINI-E footprint to add the square cut out and moved it to the Edge.Cuts layer, you can see the white square on the screenshot.
I placed the SK6812 MINI-E footprint on the back layer.
When I view it on 3D viewer it shows like it worked, the led fits and shows through the PCB, but I’m getting a lot of errors on Design Rules Checkers, if I delete the square cut out from the footprint all errors are gone, so I’m assuming by the errors text that something is touching or too close to something else that shouldn’t, I’ve been learning kicad just for the last 5 days so bear with me pls

The cut out area has no clearance (I.e. is touching) the copper pads of your footprint. The default set up requires a gap of at least 0.5mm between an edge cut and copper, hence the error.

Two things to note.

Firstly - the reason for needing the gap is that edge cuts are made with a rotary cutter and if this touches any copper the tool gets bunged up with a sticky copper smear and your tool life sharply decreases - and may even break so don’t try and reduce the minimum gap to zero to avoid the error - it won’t end well.

Secondly, because it’s a rotary tool, you can only have rounded corners as the radius of the tool will limit how sharp the corners are - probably at least 1mm if they use a 2mm diameter cutter, maybe more.

You might find that it is easier and just as effective to pop a round hole through the board with adequate clearance from the pads. Your ‘square’ hole will likely end up virtually round in any case because of the cutter size used. I suspect the light effect will look the same whichever you use.