Convert from e-Sword .bblx format to .epub. Bibles incorrectly show non-standard letters (čćšžđ)

I converted 3 modules from .bblx format (e-Sword). 2 Latin, Croatian and 1 Cyrillic, Serbian. With "Simple Bible Reader 4.4" I converted .bblx to .ont (The Word Bible). Then with the help of "BibleMultiConverter" I converted .ont to .epub (EquipadEPUB). Finally, with the help of "Calibre" I set the metadata (Title, Author, Language, Cover photo).
Both Latin Bibles incorrectly show non-standard letters (čćšžđ). They are displayed in the form of several numbers and letters and the sign ?. (š - \u353?) (č - \u269?)…

The Cyrillic Bible is fine.
In "Simple Bible Reader" I checked .bblx and .ont. Both are fine. The letters are fine.
In "Calibre" .epub (EquipdEPUB) the letters are good.
On iPad I open .epub (EquipdEPUB) with "FileBrowser Pro", letters are fine.
I think the Equipad is well tuned.
I don't know what the problem is. Can you help me?
Best Regards!