Am I allowed to use Cacao from Lick as Taste corrigens for a omeprazole suspension for a child of 2.5 years, with whom Choco is one of the few flavours, who likes to lust...?

I don't know the properties of this product. It is known that some flavorings affect the stability of the omeprazole. I suspect it is about acidic products. You should request the technical data sheet from the company and ask how much the pH is. Lick is a company based in Wallonia. So at home.