Matt wrote:

"The perfect functionality might be like my iPhone, with artificial intelligence suggestions for chords as I type."

I WOULD NOT want that functionality unless it was an option I could turn off.
For me, those "auto complete" functions are simply a nuisance.

I thought I had added the "white letters on a light background" issue to the Wishlist some time ago, but I can't seem to find it.

I like jford's idea of seeing what you type, right in the cell.
If not, then Matt's "warning" or "error" message seems more suitable than just ignoring a wrongly entered chord.

LLOYD S