Hi Danny, I tend to agree with your assessment of Yamaha’s Latin styles.
I own Yamaha, Korg and Ketron keyboards. They have their pluses and minuses
with Latin. For tropical Latin ( salsa,merengue,bachata, cha-cha-cha ) Ketron is the leader by far. For Brazilian bossa-nova I prefer the smooth sound of Yamaha. Korg does a very nice job with tropical Latin and regional Mexican, but I don’t care for their bossa nova much.

I must say Yamaha has improved greatly especially with the regional Mexican styles. For banda, norteña, and mariachi Yamaha is at the top, thanks to Manuel Durante’s amazing styles. Very impressive and authentic.

Also I like Yamaha’s audio styles for the cha-cha-cha and salsa. The percussion sound and feel really adds a lot.

Let me add, with Yamaha, for certain styles like cumbia, you must find third party styles and not use the poorly constructed built in styles that come with the keyboard.

But in the end it comes down to the player. If you can play Latin well, and sing well in Spanish, any of the brands will work out just fine.
It not the keyboard, it's the keyboardist.