As you know, for the Hebrews, the rule was better late than early. The ancient Hebrews would delay by one month where doubt was involved.
Are you referring to the Mishnaic calendar? The Tosefta says nothing about "doubt" that I can find though it says that the year may be intercalated for practical reasons. Maybe this is what you mean by "doubt"?
In any case, there is no evidence, other than the wishful thinking of the Mishnah itself, to suppose that the scheme of the Mishnah/Tosefta was used in Herodian times or earlier. It is known with certainty that the Jews of Elephantine, in Egypt, were using a local adaptation of the Babylonian calendar in the Persian period. A form of the Babylonian calendar seems to be presupposed by the First Book of Maccabees. How do you know that the temple priests of all postexilic periods never once used the Babylonian calendar, which by Seleucid times was intercalated according to a fixed cycle, rather than on any empirical basis? All "doubts" had been resolved by the fixed intercalation scheme, as they were in the much later mathematical Rabbinic calendar.
Orthodox NEVER have it early by Hebrew standards. Your admission of 2019 just proves the point.
You have not previously made any statements about the Julian paschalion. If you want to discuss it, please clarify your position. What is "it"? What "point" does the Gregorian lunar calendar for 2019 prove?
Your previous statement was:
14 Aviv/Nisan was never a full moon by our modern definition. This is because the new moon (1 Aviv/Nisan) was not, in ancient times, the dark moon, but rather what we call the "young crescent."
Note the word "never". This makes your statement an extreme statement. Your are stating that no lunar calendar which had a month called "Nisan" ever had the true full moon on the 14th of Nisan, at any longitude from Susa in Persia to Cape Clear, Ireland, throughout the entire history of such calendars up to the end of "ancient" times. You should present evidence, not just assertions, for this extreme claim.
Even if your words are not interpreted so strictly, they still don't hold up. You state that the 14th of Nisan was "never" in ancient times a full moon, because
in those days the lunar month began with the new crescent. This statement is (as I have shown) internally inconsistent. It is precisely when a lunar month begins near the new waxing crescent that the full moon comes near the 14th day. It is when the day of the conjunction is counted as the first day of the lunar month that the full moon will tend to come later than the 14th day.
Was this what you were actually trying to say, even though you ended up saying the opposite? You seemed to base your assertions on the linguistic fact that the phrase "new moon" nowadays often means "conjunction". This is true, but this fact has no implications for the mathematics of any lunar calendar, past or present. Each calendar's arithmetic must be examined to determine how its "new moon" relates to the conjunction, regardless of what "new moon" may mean in other contexts.