It isn’t flirty, “super cool” sounds like she’s taken a pic of a sunset or a cat or a party or something. “Hot” is a good start, or something like “wow”, or “omg” or any combination of 😍🥵😳💗🔥💦🍆 works. You could try making a joke but the punchline has to imply you like what you see.

The recovery was actually pretty good though, it’s funny and it makes it clear that the person wants to flirt, because they regret not flirting and they actually would like to sex. I would go on to say something that implies my brain short circuited because I wanted to sex her that badly. Something like, “In my defense I’ve heard people can’t make words good when they’re extremely horny, so please take that into account”.