If there's a source stating them read no further, and I'd just ask to see it. If not I'm going to lay out my confusion on how color 10 is an Elmot reference over a Yukata Anthuria Reference.
Looking at the primary color, the black is a warmer more saturated black. Elmot's is noticeably less saturated. Going in and comparing the colors, Yukata Anthuria's fits and Elmot's sticks out. This color is pretty much exactly what Anthuria's Yukata outfit's is. On hair color, Elmot's hair is darker than color 10 in fact both are due to the way versus is, but Anthuria's is closer to the lighter hair color. This could go either way. Big thing next. Elmot's eyes are orange-yellow. Color 10 is red. Anthuria's eyes are red. The white coloration on the clothing can be relayed to the white pattern in Yukata Anthuria. Elmot's only outfit with white is his Blazing Teacher version. Next the tail. It starts red and goes orange. This mimics the fire tail design of Anthuria's base version, and that design was carried over into her Yukata version. Elmot doesn't really have anything here aside from the flame motif they both share. The gold hair decorations fits Anthuria's which while less pronounced in her Yukata version still is present. Elmot has a gold trim on his hood. It's a toss up but thematically it fits Anthuria more. Which happens because Anthuria is also a dancer, making it far more likely she'd get a reference in Yuel's colors than Elmot. Ultimately this is my stance on why it is not Elmot but rather Anthuria. In closing the biggest arguments here are the Eye colors, the tail colors, the day and night color difference with the black, and the fact that Anthuria being a dancer makes her getting a reference far more plausible than Elmot.