I just got a couple of new eyelet-ed rims, and notice that on just one eyelet the 'lip' is partially missing, or deformed on the inside (hub) face of the rim. It makes a C rather than the O made by all the other eyelets. On the other, tire, side of the eyelet all looks well.

Returning the rim would be a PITA for a tiny cosmetic matter that will be unnoticeable to all but the closest inspection when built up.

Given that the tire side is carrying all the load and the hub side of the eyelet serves only to hold the eyelet in place when not laced, I am assuming this is purely cosmetic and the rims are fine to build up. Would I be correct?

36h, offset center 'light touring' rear with a 9-speed hub, if it makes any difference.

The only purpose of the rivet head on the hub side of an eyelet is holding the eyelet in place until the wheel is built. It's what makes the difference between an eyelet rim and having to add washers by hand as you build.

So, if you're OK with the imperfect cosmetics than no sweat and you can build with confidence.

BTW- the market is more finicky these days, but in the past, rims commonly had a decent number of malformed hub side rivet heads.

the piece is essentially a tubular grommet, as said above its rolled over in the rim hole.

Excellent. Thank you, FB and Bob.

Spoke tension should hold it in place.

As long as there aren't any cracks in the aluminum around it, you should be fine.