I don't want to modify the original in question. So here are a few errors I found:
He was the son of Robert Jacobs 1544 - 1628 Alice Goodman Jacobs born 1540<ref name ="heritage" />
Extra space before the equals symbol. There are several like this and, to be honest, I don't know WikiText well enough to know if this would break the object declaration. I know it would in some markup languages. (Note: I think this point is moot. The space doesn't seem to matter.)
<ref>Acts of the Privy Councils, cited by Kenneth Jacob</ref>
No prior "ref" established, so this element was never defined; no "name" parameter; no quotation marks bracketing the element.
<ref>British Library, Manuscript Book of John Philpott of Dover, Egerton Manuscript 2120, cited by Kenneth Jacob</ref>
Ditto. There are several like this. In short, the markup in this profile looks sort of a mess. Best to go through everything line by line rather than relying on text searches, I think.
Edited to add: Not WikiTree specific, but I've found it handy; same general markup structure: https://en.wikipedia.org/wiki/Help:Wikitext#References_and_citing_sources