>>96897860
>they are half-elves in typology
Source please.
As a general rule, being half-anything is a matter of perspective. Elf + human = half-elf is the human-centric point of view that most other races copy due to human hegemony but for elves they are half-human.
Mul gets around that by using an obvious shortening of mule, which coincidentally was spelled mul in Middle English though I don't expect the TSR guys knew that, or mulatto which is of course an important word in slavery and that I do expect the TSR guys knew.
For elfling both parents are non-human and there is no general reason in D&D to prefer the elf heritage over the halfling their crossbreed. For elves they are half-halfling, and for halflings they are half-elf. As is made clear in the novels and Dark Sun material, elves and halflings despise each other and the novel's protagonist being a elfing is a unique event. From an exegetic viewpoint we know that halflings were the original inhabitants of Athas but that's a very thin reason to generally prefer the half-elf heritage here.
>Age as half-elf
You do remember that elves only live to 140 in dark sun don't you? And halflings also live to 140? And that Athasian half-elves live to about 100?
There's no universal law that says crossbreeds have to live and age as parents but D&D has the trend that hybrid lifespan is intermediate to the parent races. E.g.,Athasian and generic half-elves, muls, half-orcs. Why would your source wilfully change that pattern and have elfling live less and age worse than both parents?
>those ability score adjustments
You do realise that half-elves get
+1 dex because elves get +2 and humans get 0 and the mean is +1. There's no int adjustment for half-elf because the mean of 1 and 0 is 0.5 rounded towards 0. Elflings should not get +2 wis but rather (2 + -1) / 2 = 0.5 rounded to 0. Averaging +2 dex and +2 dex to give +1 dex is bad.
Overall they should get -1 str, +2 dex, -1 con
Like I said before, source please.