Quo opera equatorius laborat? Quo instrumento equatorium resarcit?
It would seem that they can patch their equatorium by simply engraving
some new dates. Did they have resedit in the 1600's? 
In any case, such a UI patch should already have been performed: the
British didn't adopt the Gregorian Calendar until 1752, so the nominal
inputs should have been changed then. (temporalization? were there t13n 
consultants during the 16th-18th centuries?)
 it would appear so: "+resedit +Aeneid" shows that a resedit was
not unknown to Vergil.
 according to <http://shell.ihug.co.nz/~hermetic/cal_stud/cal_art.htm>,
T13N was quite the political process in old Rome:
>Another source of uncertainty regarding exact dating of days at this
>time derives from changes made by Augustus to the lengths of the
>months. According to some accounts, originally the month of February
>had 29 days and in leap years 30 days (unlike 28 and 29 now). It lost a
>day because at some point the fifth and six months of the old Roman
>calendar were renamed as Julius and Augustus respectively, in honor of
>their eponyms, and the number of days in August, previously 30, now
>became 31 (the same as the number of days in July), so that Augustus
>Caesar would not be regarded as inferior to Julius Caesar. The extra
>day needed for August was taken from the end of February. However there
>is still no certainty regarding these matters, so all dates prior
>to A.D. 8, when the Julian Calendar finally stabilized, are uncertain.
 Meta-trivia: It has been claimed that trivia is derived from
"tri via" ~= "three roads" ~= "crossroads" (well, Y rather than X),
because the gossip exchanged at crossroads is not important.
Etymology, or Just-So Story?