holy hell Danmaku shadowbuffs are real and they are insanely good.
Looking at Sleepy now, I'm pretty sure he'd end up being viewed a lot like Jaye- Six star masquerading as lower rarity. His kit is still a little clunky, but honestly, I think that's for the best; He basically has a prototype Last Line of Defense on S1M3, which...ironically, considering his character, the best thing to do is to just instantly give up on using the skill; +140% ATK and 70 ASPD for 20 seconds basically turns him into a burst bomb on everything unlucky enough to be in his range (Though I don't know if he'd be regaining SP during that time or if it'd basically turn it from 'ammo skill' into 'duration skill'. Hopefully the latter.)
Meanwhile, Don't Disturb Me is more of a...technical tool. It's good all the same. He has good debuffs and pseudo true damage (fitting, considering his LoR passive), which I feel can be really easily exploited with any multiple-hit enemy. Secondly, the cancel effect has an interesting potential tech- Invisible enemies. And, ofc, Invitation to Wine enemies but invis is more common. Since most ranged attackers rely on tracing the location of an enemy, even 'burst release' skills like Horn's Tempest Command rely on hitting 'a location within range', they normally don't target invisible enemies. However.
Sleepy just doesn't give a shit and blasts everything within his range with a bullet curtain and calls it good. So he might be able to mess with invisible enemies- I'm not entirely sure on the interactions with AoE ranged attacks and invisible enemies as a whole.