The exegetical is also critical to choosing any translation of Tathāgata over another. One can't, nor shouldn't necessarily, always rely upon etymologies, especially when they are conflicting or varied.
That's just part of translating, if we could make meaning for meaning translations perfectly then they wouldn't be two different languages, they'd be one.If only
everyone knew Sanskrit, we wouldn't have this problem.
The whole point of language is to represent the world, to paint a picture. I find this very in line with Buddhist teachings on conventional and ultimate truth, as Wittgenstein says,
PI wrote:1 The world is all that is the case.
4.01 A proposition is a picture of reality.
4.0312 …My fundamental idea is that the ‘logical constants’ are not representatives; that there can be no representatives of the logic of facts.
4.121 …Propositions show the logical form of reality. They display it.
4.1212 What can be shown, cannot be said.
4.5 …The general form of a proposition is: This is how things stand.
5.43 …all the propositions of logic say the same thing, to wit nothing.
5.4711 To give the essence of a proposition means to give the essence of all description, and thus the essence of the world.
5.6 The limits of my language mean the limits of my world.
When reading the text in Sanskrit, the picture that arises in one's mind should not be different from the picture that arises in one's mind when one translates it in English. However you do that, doesn't really matter.
The problem is of course when you have multiple pictures in your mind from one word, in which case context probably is what matters most. If the context is such that the Tathāgata is described as neither coming nor going, then the translation "one who arrived at truth" probably isn't as vividly illustrative of the point as "thus come one" or "thus gone one."
The point really is to help others by translating. While people are of varying conditions at present, the potential of their minds is all the same. But to adapt to their conditions, we must make translations easier to read for newcomers to Buddhism, while also sometimes catering to the experienced (I am not suggesting that CamelCase makes things any easier at this point). One must of course be sincere in this, and not condescending.
Some translations are contextual to certain spatio-temporal situations, and only understandable by the experienced, others must be easy to understand by the inexperienced in the present time and their place - academic settings often distance one from understanding the difficulty which some people may have. At the same time, we mustn't abandon the subtleties of the original language, so that when someone studies the text again and again they might learn something new each time. One must also not lose the embellishments at the same time.