Maybe she was taking Germans out of England to Germany.

FROSSOULA was definitely the first ship I mentioned, whose name was transliterated erroneously from Hebrew to English.
Since Hebrew has only a couple of letters as vowels (the others being similar to accent marks), and P and F are the same letter in Hebrew (one with a dot), it is easy to see how PRESLO could be the same ship. When transliterating to a proper name, there is little guidance to get back to the original.
For instance, the CHEPO became GEPO and JIPPO in transliteration.

And I think SYROS was probably called OSIRIS.

But the other two, and some others, remain mysteries.

Paulh