does her swearing at a non sentient creature detract from kled's crazy in any way? if so, how?
Yes, because it's not what she's swearing at that matters in this case by who hears her. The minions won't draw the connection and determine what's socially acceptable in Runeterra, but we will, and as soon as we conclude it's ok for any edgy/rebellious characters to swear then half the lineup should be swearing, not just one girl.
because league doesn't have room for more than a fraction of a percent of swearing? why does kled have to be the only character with an edgy repertoire?
No, Kled doesn't have to be alone in swearing, but the swearing should add something substantial. You're in a universe where drunks and sailors aren't swearing in their normal conversation (at least not in the game). Swearing still packs a punch in this setting, it's not casual.
As for edgy, if all you can do to be edgy is swear casually you're doing it wrong. Think of some skinny, pale nerdy guy with big glasses and a nasally voice saying those lines. Is he edgy? No. Conversely you can be edgy without swearing, which is what all of Xayah's other lines point to and why the removal of the lines don't hurt her in the slightest.