If your gf naturalized in 1927 than your gm did not automatically become a U.S. citizen. Even if they had both been living in The U.S. at that time, she would have to apply for citizenship separately. If he naturalized prior to 1922 it would have been different.
Of course, the Czech government may or may not have known about the change in U.S. naturalization law, or just may not have cared.
Searching: RATOWSKY / CHAIMSON (Ariogala / Ragola, Lith.)
WALTZMAN / WALZMAN (Ustrzyki Dolne / Istryker, Pol.)
LEVY (Tyrawa Woloska, Pol.)
LEFFENFELD / LEFENFELD / FINK, KALTER (Daliowa/ Posada Jasliska, Pol.)
BOJDA / BERGER (Tarnobrzeg, Pol.)
SOKALSKY / SOLON / SOLAN / FINGER(MAN) (Grodek, Bialystok, Pol.)
BOBISH / APPEL (Odessa?)