I feel like Eliška is the Czech/Slovak counterpart of Ava or Mia. I did research on this name and it's common among young women below 30. Personally, I think Eliška is a lovely name. I've always preferred it to be a name on its own.
With 56 052 bearers, Eliška is the 53rd most common feminine given name in the Czech Republic (2014 Data). With 832 bearers, Eliška is the 347th most common feminine given name in Slovakia (2014 Data).Source: https://forebears.io/x/forenames/eliška
Eliška von Görlitz of Bohemia, Duchess of Luxembourg (listopad 1390 – 2. Srpna 1451) was duchess of Luxembourg in 1411-1443. She was only daughter of duke Jan von Görlitz, son of Karel IV and Swedish princess Richardis of Mecklenburg-Schewerin.
A famous bearer: Eliška Přemyslovna - daughter of Czech king Václav II and Guta Habsburská (20th January 1292 - 28th September 1330). Wife of Jan the Luxemburg.