My experiment this year will be to use Excalibur IX for the first time. Time will tell whether I notice any improvement in growth and/or blooming. I disagree with folks who believe that high phosphate fertilizers are necessary (or even beneficial) for plumeria to bloom well (or for that matter, any other flowering plant). I experimented with bloom booster fertilizers a decade ago, fertilizing half my plumeria with two of these and the other half with a balanced formula. I saw no significant difference in blooming but did see a difference in plant growth and health. I saw less growth when using the bloom booster as well as smaller, more yellowed leaves. That was simply my observation and needless to say, this isn't anything scientific. Though I've grown and propagated 1000's of plumeria over a 30+ year period, I would suggest that you ask successful, commercial plumeria growers what they use on their own plants. I think you'll be surprised with their answers. Tex at 'Florida Colors' and Brad at 'Brad's Buds & Blooms' (the two largest commercial plumeria growers here in Florida) will probably be glad to tell you how they fertilize.
By the way, I fertilized all my plumeria (only 55 now) with Excalibur IX yesterday.
I would venture to guess that you might get better blooming if you begin your fertilization using a balanced formula and then after a month or two, augment that with a bloom booster fertilizer. The balanced formula jump-starts your plumeria growing and leafing well, and having healthier plants should increase the likelihood of blooming. I've never augmented my plumeria with bloom booster fertilizers though. That single year of using these fertilizers is all I have to go on.