When GIMP starts up, it changes its interface language to Portuguese if that keyboard is currently active. This should not happen. My OS X installation has English set, so all interfaces/menus are English, regardless of which keyboard language is active.
Same here with 2.8.18p1. I deleted the extra keyboards, restarted, and reinstalled GIMP, but the interface is still partly in Hebrew, partly in Icelandic. Only English has ever been active while installing or running GIMP.
I was bitten by this bug when I upgraded from macOS 10.11 to 10.13 (GIMP used the secondary [of two] instead of my primary language set in macOS Preferences). I noted, with dismay, that GIMP 2.1.18p1 removed the Laguage setting from its preferences!
This bug does not appear in GIMP 2.10.4, however.