Hello Kathleen !!
I appreciate giving me invitation, it would be really nice to add anything i can.
I have no access to any records of Łańcut/Przedmieście, i think only way of obtain it is go to the church (back office) and ask priest. There i would need a help, since I was 100% sure there werent online vital records, how did you get your one, i see on Familysearch only military records for Łańcut.
It is a bit funny but i like the way you call grandparents :) Judek is i suppose a try to pronounce Dziadek which is polish Grandpa. Babu is Grandma, polish Babcia (or informal Babunia)
A surname Jabłoński comes from a word "jabłoń" which means apple tree. It has line thru on "l" and vertical line over "n" (ł and ń) which are polish diacritic letters. Surname ends with letter "i" but many polish surnames are changed to be better pronounced (or showed) in USA, they change from -ski to -sky. To be a bit exaggerated, you can read aloud a word Yabwon(i)sky (soft n) as in english and what you hear is more or less a polish pronounciation. Alternatively use a online service text-to-speech like IVONA.
Additionally, female versions of surnames ends with -ska , -cka of their male counterparts -ski, -cki. Take it in mind querying Ellis island manifests. So valid search would be for Katarzyna Jablonska, or change to "start with" and search for no-ending-surname Jablonsk.
Paweł and Katarzyna went to USA with their daughter Karolina as we see on manifest. But the book author Mr. Trześniowski wasn't certain at a time of writing about Karolina and he mentioned second child Stanisława (it is a daughter) and he put a b. year 1908 next to the name. So its not hypothetical name but real child. Stanisława was a girl.
Stanisław (Stanislaus, Stanley) is a boy name. There is no female version of Stanley in english but it is in polish though.
I hope i answered your qestions :) I will send a scans to your email in a short time, and good luck :)