apparently, to a southeast asian, "guava" is a generic term that refers to any kind of large citrus fruit, while in north america it refers to a specific species native to mexico. in an act of reverse-colonialism, mexican guavas have been introduced as a plantation species in hawaii and vietnam and have displaced some of the native fruit. a pomelo is a native south-east asian citrus variety.

somebody probably made an honest mistake and the actual truth is that, to a southeast asian, a pomelo actually is a guava.

they're wrong, but that explains it.