in Brazillian portuguese it had a completely different meaning, and it was used for disambiguation of the pronounciation of some words, in short "gue" in portuguese can make a ghe (gh as in ghost) or a gue (gu as in guatemala), a similiar thing happens with "que", this umlaug looklike was meant to make clear that the "u" was to be pronounced, so we had spellings like "freqüencia"

THIS SO MUCH THIS, LOCALIZED SHORTCUTS ARE PAINFUL, I CAN NOT FIND WAYS TO FULLY EXPRESS MY HATRED FOR THEM AS SOMEONE WHO HAD TO USE OFFICIE 365 IN PORTUGUESE also btw mnemonic shortcuts were a mistake