Partial Answer
I think the ultimate answer is
Pope Gregory XIII
Who was born as
Ugo Boncompagni (initials U.B.)
The grid
If we highlight the diagonals in each quadrant as indicated by the right-angle triangles ($\sqrt{a^2 + b^2}$ indicates that we are looking the hypotenuses of each triangle) then we get the following

Reading from the left side and going clockwise, the first grid reads
BISHOP OF ROME
which is another name for the Pope. The initials grid reads
JFMAMJJASOND
which are the initials of the months of the Gregorian calendar, in order, the calendar introduced by Pope Gregory XIII
Bottom image
I can only think that the cross refers to Easter and the computus (calculation of the date of Easter). There are calendar based algorithms which change depending on whether we use the Julian or Gregorian calendar so this would hint at the symbols on the cross. Also, the "+1" might indicate the presence of a leap year (hence the meaning of "sometimes").
This part is not fully formulated which is why I've marked as Partial Answer.