I think using inspiration from African ethnic groups would work well for Wild Elves, Copper Elves would probably be more like mixed background people because Copper Elves are exactly that, a mix of Wild Elves and the other Elven types. Greek ethnic inspiration seems like a good fit for Sun Elves IMO. Moon Elves and Star Elves physically are probably the ones to give the more anglo caucasian appearance. If the were to branch out further, I'm not sure about "asian" (which is a very generic term sadly) inspiration for any of them, Eladrin might be an interesting one to consider tying a bit of Japanese influence to, considering their art in Volo's Guide. Drow would potentially fit following the same pattern as Wild Elves, considering their background as the Dark Elves were originally from the same regions as the Green/Wild Elves.
However, with all the above, I think you'd still want to:
adjust eyes to be more almond shaped
add sharper, more angled, more defined jawline and cheekbones
make the nose a little narrower
reduce chin width to accent the more angled jawline
increase the angle of brows slightly
make the face a bit more slender
I like your ideas and would be happy to see something like this in-game in the future
So, what would the above mean for current character creation options for currently available races?
well... High elves would have more european features, with them ranging from more anglo looking to greek/italian. The colourations would be: Skin: Pale, tanned/bronze tones, pale skin tones with a blue hue, pale skin tones with a purple hue. Hair: Blondes, Browns, Blacks, Reds, Blues, Whites, Golds, Silvers, Coppers Eyes: Blacks, Golds, Silvers, Blue/Green with Gold Flecks, human colours.
Wood elves would be more african and mixed heritage features. Their actual bodies in theory, if a slider system was added, should probably have slightly more room for broader, sturdier appearance than high elves. Skin: tanned/bronzed through to very dark browns Hair: Copper, Brown, Blond, Black, Gold, Reds Eyes: Greens, Hazels, Browns, possibly silver, possibly black
Lolthian Drow would be again more african for their features like Wild Elves, they should be shorter than high and wood elves. Skin: shades of obsidian, purple, grey. brown or blue undertones, possibly include some lighter versions of those too as a nod to a lot of art. Hair: various whites and off whites Eyes: Reds, Purples, Ambers
Seldarine Drow should be pretty similar to Wood Elves for options, but be shorter like drow and lack the mixed heritage faces.
Reminding again that those real world ethnicities would be a starting point for elven faces, but they'd all be adjusted based on the bullet point list above.