Just out of curiosity, why are there no flat keys and ability to construct chords? The website looks slick but I think from a functionality perspective, there

Just out of curiosity, why are there no flat keys and ability to construct chords? The website looks slick but I think from a functionality perspective, there is a lot lacking with this library. I am also not sure what the value of MCP is here. Without flat keys (and double sharp/double flats), there is quite a bit of harmonic space that is omitted.