I have been following this topic, but due to other commitments, I haven't had time to participate. But I contacted one of the techies, whose mother tounge is Spanish, and asked about the two upper case letters that didn't validate. Here is the reply I got:
"
Hi Inger! I have taken a look and I cannot see those kind of errors with those characters, not on his pages neither on mine (https://validator.w3.org/nu/?doc=http%3 … index.html). Only thing I can think of is that he has copied those characters from another source. For example I noticed MS Word documents transforms a bit the chars, like using a different “angled tick” which it could be not valid indeed (even though those should be transformed in SD).
so maybe if you could ask him to post the actual link of the validator with the issue maybe will give a hint… but from a quick glance it should not be an issue."
Note what he says about copying/ pasting text from MSWord. Don't know if you did that, of course.