YT 1362 as an upper end limit to their birth year
Oberiko, the problem I have with the note you recently added (the one where you point out that Galadriel was the youngest of the House of Finwe) is that Tolkien didn't stop tinkering with the genealogy of the House of Finwe after he wrote that line.
In fact, seeing as Aredhel is older than Argon (a late addition to the family tree), and the fact that she was born in YT 1362 (the same year as Galadriel according to AAm), your addition is incompatible with some of Tolkien's later writings which TG seems to have adopted.
And that is without even mentioning Celebrimbor, Idril and Orodreth, all three of whom are a generation below Galadriel, and I find it implausible that all three are older than her - again, this issue ultimately stems from the fact that we're mixing various different sources from various different periods of Tolkien's writings: at the time that the note you added was written, Celebrimbor was not yet a member of the House of Finwe, Argon did not yet exist, Orodreth was an older brother of Galadriel instead of her nephew, leaving only Idril as a member of the House of Finwe potentially younger than Galadriel.
All in all, I don't think you should be setting the upper limit for the twins' birth year on a text contradicted in multiple ways by later writings, writings which TG considers valid enough to include in the main text of various articles.