I agree, the Rhyncattleanthe Momilani Rainbow is one of the classic Cattleyas that most Cattleya lovers know about. It was very special back in it's day. First awarded to a Phelps Farm clone back in March of 1995, it was something that had not really been seen on the "Orchid Scene", a tri-lipped Cattleya with good form, substance and texture. Size was pretty good back then. One thing that is interesting though is that not one of the award descriptions that I looked at, 6 out of 18 total awards, mentions fragrance. Interesting. Why is that? We do not assign points, plus or minus, for fragrance.
But man, look at your images, that lip, with two petals mimicking the lip, nice full shape, good size and a nice arrangement are some good reasons to award this hybrid. A few clones were mericloned like crazy!! I was in just about everyone's collection as something very unique and beautiful back in the day.
I also agree that those look like buds coming on your walkeriana, still is my number one favorite species. My collection would seem incomplete, worthless, without several clones!!! Congratulations on your achievement. Great job and thank you so much for sharing!!