Is it corect to say sandviș?
Indeed, it is correct.
Isn't the last vowel pronounced? Is it there just to change the sound of the "c"?
yes, it's there to change the sound of c. it's also used to change the sound of g. also I see many words are not pronounced very well in this course. also the word should be sandwiș or sandwich
Making me hungry there. :)
Why is sandviș not recognized as correct?
It should, report it if you encounter it again.