It sounds like at least one person (if not more, wouldn't be surprised if it's more) sent Pan4 (the artist who draws the Lout of Count's Family manhwa adaptation) messages on Naver about why manhwa!Erhaven has curved instead of pointed ears, so Pan4 explained that when designing Erhaven, they asked Yu Ryeo-Han's advice, and Yu Ryeo-Han suggested the curved ears rather than pointy (elf) ears.
I saw a lot of people get pissy about him not having pointed ears, so it's really shitty this got back to Pan4. He has a nice design. Leave Pan4 alone. Other folks have pointed this out, and so far as I can tell, there's no mention of what shape his ears are, at least in the Seven Seas translation volume 3, where the English translation currently ends (not that the translation is perfect, I've found a number of issues with it, but it's what we have). Cale describes him as an elf for a bit, but he doesn't say why, other than emphasizing Erhaven is pretty like an elf. Other folks have pointed out that people call Erhaven an elf because he's beautiful, not necessarily because he has pointed ears. Maybe it gets indicated later in the story, but I have no recall of that happening.
If you want Erhaven to have pointed ears, nothing is stopping you from giving him pointed ears. Just make fanworks where he has pointed ears and move on. Like it's to the point that ENCELADUS/encel_uuu (a popular Erhaven fanartist) is considering removing their Erhaven fanworks of him with pointed ears because people keep mistaking their pre-manhwa Erhaven arrival designs as official designs.
Please don't harass the manhwa artist about it.