>I need to do it through a program when read file with fopen() and fget() etc. In attachment is a sample file. Question is how to recognize (and convert) row 4 "Нови Београд" to "Novi Beograd"?

Well convert everything, as a single string - latinic will not be changed by chrtran(). In bajagi code:

c=filetostr("from_file_cyr.txt")
lcOut=chrtran(c, lcCyr, lcLat)
lcOut=strtran(lcOut, "Љ", "LJ")
... other pairs here...
strtofile(lcOut, "to_file_lat.txt")