This board is a Waldorf Rompler, I used this together with the Waldorf Nano in my CME UF7, but I didn't really like the sounds to much. It had a couple of decent piano sounds, but overall they were a bit to bright, and others very flat. It didn't give a realistic enough piano sound for me to use in a serious context, I would only use it for simple practice here and there, but honestly I would rather have spent the money on an actual synthesizer or software piano even.
It's maybe a bit better sounding than pianos that you would find in an average synthesizer, but the price of this and Waldorf Nano together doesn't do justice for what sounds you get.
Consider a desktop synthesizer to put on the CME instead, like Waldorf Blofeld, which is the same brand with a lot more to offer, also a couple of OK piano sounds, but more tweaking possibilities.