Is the CBX-T3 an XG capable device?

No. The CBX-T3 and TG-100 were designed and created without the XG standard in mind, having been created prior to the standard. However, through the forward compatibility of the XG standard, GM music can play on an XG device with little trouble, but XG music won't necessarily play on GM devices like the CBX-T3 and TG-100.
A page for The Yamaha CBX-T3 Homepage.
© 2004 Noby Nobriga