I finally checked my husband's Memorial Day email from FamilySearch. Here are the results:
Ancestor Column
3/10
(Seriously!) The rest may be relatives on a family line, but definitely are not ancestors, including the person named in the email.
Ancestor's Headstones
3/10
One of them was fun to see since I am not too familiar with my husband's colonial ancestry.
View My Relationship
2/10
The listed connection to Nathaniel Tilden (1583-1641) included an incorrect generation, but despite the error in "View My Relationship" it does look like he is an ancestor.
Total
8/30 = 27% accuracy
In Conclusion...
It looks like FamilySearch needs to keep working on its computer matching, with the caveat that since the matching is using user-generated trees, it is unlikely to reach 100% accuracy. Hopefully most people saw accuracy closer to what I saw. (85%)
I haven't kept track, but fortunately FamilySearch hints seem to have a much higher accuracy rate.