Dear Ajahn, I took the liberty of skimming through Bhikkhu Bodhi’s “In the Buddha’s Words”, looking for uses of “I” and “Tathāgata”.
According to my counting, the Buddha uses “I” to refer to himself about 40 times (39 “I” + 3 “me”). He uses Tathāgata about 22 times.
6 out of 22 uses of Tathāgata have appear, arisen or manifestation in the same sentence.
2 out 22 uses of Tathāgata are in plural, spoken by someone else, as in “Tathāgatas are awesome”.
Of course, “In the Buddha’s Words” as a sample doesn’t necessarily represent the general trend of the suttas.
Here are also some excerpts from the suttas about the Tathāgata:
“Here, bhikkhus, a Tathāgata appears in the world, […] This, bhikkhus, is the first person appearing in the world who appears for the welfare of many people, for the happiness of many people, out of compassion for the world, for the good, welfare, and happiness of devas and humans. Iti 84
So too, bhikkhus, so long as a Tathagata has not arisen in the world, an Arahant, a Perfectly Enlightened One, for just so long there is no manifestation of great light and radiance, but then blinding darkness prevails, a dense mass of darkness; for just so long there is no explaining, teaching, proclaiming, establishing, disclosing, analysing, or elucidating of the Four Noble Truths. SN56:38
I agree that Tathāgata has something to do with truth, perhaps that he is the first being to discover the truth (in a world where the truth has been lost).
What about “Discoverer” as a translation for Tathāgata?
I also think “Realized One” is good.
I guess I just feel that “Tathāgata” is tied to this narrative of a great spiritual event in the universe. I would guess that it was probably a myth that existed in the time of the Buddha, about the appearance of a great sage who would hold the answers to the mysteries of the universe, or something like that.
And also, I would be so bold as to respectfully suggest that the the Buddha usually (statistically) uses “I” and “me” when he is referring to himself, and that when the Buddha uses Tathāgata, it includes himself, but it also serves the purpose of defining what a supreme spiritual being must be like.
Sort of like taking the word ‘messiah’ and defining it to be one who awakens and teaches the four noble truths.
Anyway, there are many good options, I am sure whatever choice is made will bring much praise and blame
Edit: It’s not so cold, but there is wind and a lot of slippery ice; a perfect day for staying inside reading suttas and meditating!