Hello, S! Perhaps I can be of service. To begin with, I believe the Barbour collection transcription for Waterbury is in error, either a transcriber's error, or the original was in error. For Jaorum Matthews, I did a broad Google search, an ancestry.com search, an americanancestors.org, search, and a familysearch.org search. The only Jaorum I found is in that single entry in Waterbury Town Records. Further, I believe that the marriage did not occur in that town, but was entered there because Reuben was from there, and had parents residing there.. I interpret the entry to read Reuben, of Waterbury, married Xene, of New Hartford, in the Province of New York.
I DO find, however, a record of the marriage of Xena Matthews to Reuben Beebe on 30 March 1774 in the town of Hertford, in what was to become Hartland, Vermont. [Early Vermont Settlers, 1700-1784. (Original Online Database: AmericanAncestors.org, New England Historic Genealogical Society, 2015. (By Scott Andrew Bartley, Lead Genealogist.) https://www.americanancestors.org/DB1565/i/53409/4/72500547] Vermont was disputed by New Hampshire and New York at that time. Hertford's name was changed to Hartland in 1782, to lessen the confusion to Hartford. This explains the Waterbury entry referring to New Hartford, Province of New York.
Next, Xena's father was named Joel Matthews. The above article, 5 pages in length, reports in length the life of Major Joel Matthews. If you do not have a subscription to americanancestors.org, I'd be glad to abstract a portion of it for you.