literally the first line

string[] delimiters = new string[] { " ", ",", ".", ":", "_", "-", "/", "", ";", "!", "?" };

these are not the only delimiting characters, you need to split on everything that isn't in [a-zA-Z] and '

Write a BF interpreter which according to the test comment // Echo until byte(255) encountred it tries to run this BF code ,+[-.,+] on a string Codewarsÿ which copies Codewars to the output, stopping at ÿ.

edit: ÿ is only what you might see in a hex editor where the byte is 0xFF, and it appears here. 0xFF a.k.a. 255 is what really matters, because the 2nd + BF instruction increments it, and it wraps around to zero, so the following ] instruction advances to the end of the program instead of jumping back to the [ instruction and running the loop again.

edit++: I mean 'jumping back to the next instruction after ['. I don't really know BF.

whatchu talking about man