Big upvote!
Clue scrolls should be readjusted for monsters. No one monster should be so far beyond the normal rate that they could be recognized as extremely fast source of clues. This would be monsters like blue dragons that drop 1/22, while some similar monsters are ~1/100, and catacomb monsters that could be over 1/600. Also worth mentioning that yaks drop both easy and medium clues at a super low rate. Clues are already easy enough, and now that they stack, they shouldn't have extremely fast methods to get them.
I don't know if I particularly agree here though. clue rewards seem fair for how frequent you "can" get them, otherwise they wouldn't be worth it imo. I wouldn't be opposed to a semi-low drop rate across all monsters and raising it for the easier ones so slayer in general gives a very similar amount what we have now or raising the bonus effects of the ROW so it becomes more viable.