Unicode \u2019 error

Hi, I am running a cURL to return data. I am getting a txt file that I then translate in to CSV by using this function:

$xslt = New-Object System.Xml.Xsl.XslCompiledTransform;
$xslt.Load($xsl);
$xslt.Transform($xml, $output);

The problem is that I am returning characters other than English, and I am getting an error related to the unicode \u2019.

What would be the best approach to this. In Unix I would use xtslproc and recode html the text file, but somehow, I don't find any equivalence with Powershell.

Thanks