I have run WC3 and it has thrown up a few errors. Very simple ones like
Line 99, Column 48: there is no attribute "bordercolor"
Line 100, Column 41: there is no attribute "height"
Line 308, Column 61: end tag for "sc" omitted, but OMITTAG NO was specified
Line 148, Column 43: element "o:p" undefined
There is about 25 over 2 documents often the same on each one.
This one is a very small project but I just do not have time to go through.