Look, as someone who also grew up in the USA with the terms liberal and leftist being used synonymously, it's us who use it the wrong way. I also have a tinge of offense when liberal is used as an insult or with negative connotations, at least at first. Then I remember what liberal actually means, what the people using it are probably saying based on context, and carry on. We can't expect the whole world to use a word the way we're used to it when the entire rest of the world uses that word in a different, agreed upon way.