As well you might, they can only be correctly spelled in the Cyrillic alphabet anyway. Any transliteration into an inferior alphabet will lose some sound or other, because alphabets evolve along with the languages that use them. The modern Latin alphabet evolved along the Romance languages, which is why English spelling is often kludgy, and the poles have to go to ridiculous extremes to cram all the sounds their language uses into a far too constrictive alphabet for it.
As long as the letters you use make a more or less comprehensible sound, your transliteration was successful.