I'd say there are many factors that contribute to the flavor of any mango.
A perfectly ripened carrie should taste good to most palates, however not everyone is the same obviously. If they are tasting watery then I would say that is not normal. Give it another year to see what happens, personally, I think carrie has an outstanding flavor. I even bought a second tree that I placed in a large container in case I ever sell my house I can take it with me. That's how much I like it.
I have not run into a carrie with a watery taste though, I can understand how that would be disappointing.
I pick them when the skin is smooth (less bumps), when the pannicle that meets the fruit turns brown & when the fruit itself starts to turn more yellow.
Good luck!