Wheelbuilding / Wheel Building / Wheel build help

Impact damage hopefully isnt an issue as I'm a fairly cautious
But yeah, I was mainly inquiring about if there are any issues with fatigue. I'm guessing spoke holes can crack, is this a common problem?
And whats the deal with internal or external nipples, is one more suitable than the other in this instance? Or are nipple washers a good idea?

My logic is often messy, and twisted, but here it is.

Internal nipples are mainly for aero characteristics. But I used them because they require a smaller rim hole drilled, and you end up with a bigger nipple contact area. So less nasty shear on the carbon.

Spoke washers compensate for the fact that the rim drilling is unlikely to face exactly in the direction of the spoke. (the nipple face is rounded, which also compensates I guess) So again you get more contact area.

Trying to thread internal spoke washers onto the spokes of a 50mm deep rim is a recipe for madness. So use thick lube to hold them onto the internal nipple face.