Ladislaw is a phonetic version of the Polish name Władysław, which has been the name of four kings of Poland. It is derived from Slavic vladeti "rule" and slava "glory" (Behind the Name).
Zamojski is a Polish surname (sometimes spelled Zamoyski). It derives from z Zamościa meaning "of Zamość", a city in southeast of Poland, where they were the local nobility (Wikipedia).
We only know the names of the Seekers from the Polish National Team who played in the Quidditch World Cup tournament in 2014. Zamojski may have still been on the team as a Chaser. Unfortunately they lost their Round of 16 match (Pm).
Lexicon list of Chasers