Derek, there are quite a few Mexican/Spanish/Brazilian voices they put on the sx600 but not on the T5 (or it's sister product the DGX670);basically including an expansion pack in the ROM
Sounds like Viola Caipira, or Cavaco, for example.
Fun fact: PSRsx all contain Half Wah Lead & Pizzicato Glocken(from psrs970/770 and I think even s950) but the Genos does not. Even if you copy the same dsp over, the root guitar sound is still different (which you can really hear if you turn off the distortion DSP) with a very dynamic different response from any of the ones on the Genos. Why? No idea.
Why those sounds PSRsx600 aren't included on T5, Genos, DGX670, or even sx700/sx900, that's simply them putting a pack (presumably Brazilian) onto the ROM of the sx600, that's on the assumption you can put in something similar via YEM.
Mark