I may be late to the party on this one but thought I'd comment anyway.
I just completed two separate 12900K builds, both using Asus Z690 motherboards which have mounting hole compatibility for both 1200 and the newer 1700 socket AIO mounts. I used H150i Cappelix coolers on both builds.
On one 12900K build I used the Corsair socket 1700 retrofit stand offs and all is well regarding temps.
On the second 12900K build I used the old socket 1200 stand offs; I have a second retrofit coming but didn't want to wait. So being the natural born innovator that I am and to compensate for the shorter over all length of these older 1200 standoffs, I placed a spare washer over the top of each standoff before tightening down the final thumb screws.
I used four of the black washers that come packaged in the H150i Cappellix kit. And as with the first build, all is well regarding temps and both systems test/benchmark with the same min/max temps during synthetic tests and gaming tests.
I have no idea if this "washer mod" actually compensates for the difference in the 1200/1700 stand off heights but temperature tests confirm there is no need for the 1700 retrofit stand offs in this case, at least when using any of the Asus Z690 motherboards.