@Sviatogor well, as I wrote, it is a poem :) I know that you guys don’t have consonants together, like there are in the south and especially not like there are in the west. Do you have hard time pronouncing such words? Like stršljen (стршљен) e.g. it’s шэршань for you. 
Back to the topic, what’s your impression now that you have heard č and ć in Serbian. Do you have such sounds? 
btw I just saw, you have four examples of pronunciation at the beginning of this thread. (češnjak one is with strong Croatian accent)