Sin is obviously more influenced by the comics than vertigo or Felicity, because she's atleast semi-connected to a character called Black Canary in the show. But, she's an annoying generic punk/street urchin who could not exist and the lack of the character would only improve the show, which makes her name not matching more of an issue, and something I actively dislike. If done well, I don't mind characters that steal names that really make no sense for them, and Sin could have been interesting. If she was less annoying, and actually had a bit more of a point/back story, I probably wouldn't care about her having the name.
As for Felicity, I don't have any personal experience to compare her to the comic version. The comic character is so obscure that wikipedia only mentions her in the article for the TV show. Apparently, according to comicvine.com, she was Ronnie Raymond's step mother who used to get into arguments with Firestorm (and even sued him, apparently) before she became his stepmother and found out his identity).