Possibly incorrect grammar case used for Jiří

[tukusejssirs]

According to sklonuj.cz, the genitive singular of Jiří is Jiřího. I don’t say that website is absolutely correct, but it looks like it is correct.

The relevant line is located in czech-cs.txt (L63).

[igneus]

No. https://prirucka.ujc.cas.cz/?slovo=Ji%C5%99%C3%AD

"Čí je to kolo?" "Jiřího." ("regular" genitive)
but
"svátek svatého Jiří" (uninflected genitive used in some specific contexts - "svátek svatého Jiřího")

[tukusejssirs]

Thanks for the explanation. Sorry for reporting non-existing issues.

[igneus]

Ouch, I left the sentence in parentheses unfinished: I wanted to say that "svátek svatého Jiřího" (the regular genitive in the particular context) would sound very strange, signalling that the speaker is either non-native or not familiar with this layer of the language (probably lacks education above the elementary level, has not read much etc.).

[igneus]

Fun fact: the form "Jiřího" is used in the calendar of Czech Old Catholic Church. The archaic genitive "svatého Jiří" is usually tied to this very phrase and since the calendar does not use the title "Saint", it doesn't use the name's archaic genitive either.