I Frenz Josefekar 3 Austria- Please explain this 1920 Austrian Address/Location

I don't mean to be blunt, but as a basic step, have you tried Googling anything?

• Googling "Frenz Josefkar 3" yields the result that this is a likely misspelling of "Franz Josefs Kai 3," which is an address in Vienna.
• Googling "Radetzkystr 23" directly yields a result to Radetzkystraße 23, which is also a current address in Vienna.
• I guessed that the "I" and "III" were Roman numerals for numbered city districts, and googled "Vienna districts," which was fruitful:
  • District 1 is Innere Stadt, and indeed Franz Josefs Kai 3 is within this district.
  • District 3 is Landstraße, and similarly Radetzkystraße 23 is within this district.

Thank you Andrew for your gracious and helpful repy. Not everybody uses Google as their search engine.
The errant spelling was in the original US documents.

1., Franz-Josefs-Kai 3 (built 1904)
https://www.wien.gv.at/kulturportal/m19objekte/bez01/00062001.jpg

3., Radetzkystraße 23 (built 1880)
https://www.wien.gv.at/kulturportal/m19objekte/bez03/00394602.jpg

One of the things to understand with family history is how and why documents were compiled.
In this case US Immigration probably asked for the information verbally, then wrote down what they thought they had heard. In all likelihood the information on the ship's passenger list would have more authentic spelling, as it was compiled locally by a clerk more attuned to accents and local spelling.
Often also the passenger lists yield other information not recorded elsewhere.

Thank you for these thoughtful responses! The story is coming to life. The photographs are amazing -
One location looks well maintained, the other more industrial. Observations about information source is very astute. I had wondered about this. I have seen Customs and ship manifest information and wondered about their veracity. I am relying on English language sources.

The photographs are amazing -
One location looks well maintained, the other more industrial.

The picture of Radetzkystraße 23 is from 2014, when the house was entered into the (publicly available) building database of the City of Vienna. A picture from 2022 can be found with Google Streetview. The house looks pretty neat now.
https://www.google.de/maps/@48.2116333,16.390654,3a,90y,279.25h,95.11t/data=!3m7!1e1!3m5!1szp9ugCYojSahfZGcxJ5i3g!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D-5.109999999999999%26panoid%3Dzp9ugCYojSahfZGcxJ5i3g%26yaw%3D279.25!7i16384!8i8192?entry=ttu&g_ep=EgoyMDI1MDIxMi4wIKXMDSoASAFQAw%3D%3D

I am relying on English language sources.

Online translation has reached a quality which allows to understand most texts pretty well.

Most browsers have a function to translate any displayed page to English.

Thank you - I"ll look for the translate function in Firefox. Also hadn't considered the global reach of Google Maps.