The Yamaha 'ABC' method is proprietary [& iirc patented] system, so you won't find exactly the same algorithms used in other devices or software.
The method you are referring to is the 'easy-play' version of ABC. It uses a different, much simpler but less musically-accurate shorthand to play a much smaller selection of chord types [only major/mnior, 7th, iirc]. It really isn't a system you ought to use to learn how to play, it's more for 'fun.
The 'full' version of ABC requires you to state the chord you wish quite clearly; giving the system a root, 3rd, 5th + any flavour notes, before it will follow you accurately.
if you press just C it will play Unison... nothing but C's
if you add an E above it will play C Major
adding an A above, it would assume A minor, even though C is the lowest note
so to get C6 you would need to add G as well.
Source: I used to actually program those built-in styles for a living, long time ago ;)