Found this awesome paper that conducted a study on protein requirements of Cichlasoma Synspilum. Since one of this that was used to make blood parrot (which were used to make flowehorns) and is used to make kamfas is Cichlasoma Synspilum/Redhead cichlid/Vieja melanura the fish is very similar to a flowerhorn biologically. You might be already familiar with the paper already but thought it might be a good share with everyone on forum and share what I understood from it.
Here's what I took from it:
Looking at the protein efficiency ratio, most of the protein above 40% was not actually used by fish and I assume the weight gain was from lipids. The survival rate is significantly lower on foods with more than 40% protein and I would not sacrifice that for faster growth, as you have said
IMO this hobby is all about patience, and measuring success in years, not weeks, or months.
Attaching the screenshots of the research paper The dietary protein requirements of Cichlasoma synspilum Hubbs, 1935 (Pisces: Cichlidae) fry.
Reference: Olevera-Novoa MA, Gasca-Leyva E, Martinez-Palacios CA. The dietary protein requirements of Cichlasoma synspilum Hubbs, 1935 (Pisces: Cichlidae) fry. Aquacult Res 1996; 27(3):167-173.