We probably need to make a distinction here between episodic and autobiographical memory, on the one hand, with procedural memory on the other. Life events tend to get garbled in dreams, forgotten or their consequences ignored, but maybe our dreaming minds are better at remembering how to do things than they are at keeping track of what age we are, or where we live, or how many mothers we have...
Very interesting post about enhanced abilities in dreams, Alan! Me, I'm a musical dunce, but somehow my brain is able to create amazing tunes sometimes in my dreams that, as far as I know, I've never heard in waking life. There's a bit on the 3rd CD of the Beatles Anthology where John Lennon starts playing Strawberry Fields on guitar, then breaks off saying, "I canna do it." Once in a dream, I was listening to that, only instead of breaking off, he carried on with this amazing, fine, fiddly guitar playing. To say nothing of all that unconscious story-spinning and the ability to create imaginary, convincingly immersive (and sometimes downright spectacular) VR scenes that unfold in real time in as much detail as we chose to pay attention to. It makes me think of William Gibson's short story
The Winter Market, in which dreams can be recorded, edited and marketed, where there's a comment about all the unconscious talent that went to waste before this technology arrived.
I've had the experience of speaking fluently languages that I'm not fluent in in dreams, and sometimes I've woken up and been either convinced or agnostic about my performance; other times I wake up with the impression that I've been talking fluent nonsense!
Without wanting to dismiss your experience, I suppose with the dreams of colours, there's the philosophical connundrum of whether the colours you gave those names to correspond to the colours a person without impaired red-green vision would call by those names.
DreamBank has a good collection of dream reports, including a group of dream sequences from blind people, including some congenitally blind.
http://www.dreambank.net/