as you say "almost" which is also why i equivocated (which i did intentionally) in my post, with "this MAY help".

in addition, i've built a set of wheels that i didn't like because, like the OP stated, i noticed that there was a bit of thread showing. i logged onto a few spoke calc programs and noticed that some of them demanded a nipple length as a required parameter for calculating the spoke length. i also noted that a longer nipple length specified as input, resulted in a shorter specified spoke length.

soooo, i bought some longer nipples and rebuilt the wheel with no threads showing. it's still going strong.

it will be hard to convince me that my experience is misleading me. but it's possible, i suppose.

i will say this. over the years i've had occasion to buy several different extra long nipples (14mm, i think) and although they all have more threads on them than the any of the 12mm ones i've tried, there is no uniformity between manufacturers that i am aware of.