Dutch language

Dear Sirs,

My web designer says to me that because of the Dutch language in the 
website, that is the reason why there are so many errors ??


"MANY ERRORS IN W3C is because of the language being not English and 
special characters being used in the font to get the desired effect 
in Dutch. this cant be rectified either" ==> words of my web designer


Is this true ?

Thanks and best regards
Guy Hacha