I really like how you used Rhythm through the drums, the songs, and the ritual itself. I also enjoyed the use of the masks as ritual tools rather than simple disguises.
I never would have imagined a TTRPG built around performing a ritual to bring back a Great Moth, but I genuinely found the concept fascinating. The different choices of masks and drums also seem like a nice way to vary each character's role and approach.
My main difficulty was understanding how a campaign is meant to flow in practice. I couldn't quite picture how one session transitions into the next, how long a Moon event is expected to last, or how the adventures and the ritual alternate over time. Since some Moon events sound like they could become full adventures on their own, I also wondered how you keep the ritual moving forward if the group spends several sessions exploring a single event.
I also wasn't sure how the game scales with different player counts. The ritual revolves around the Seven Drummers, but I couldn't figure out whether the players are meant to portray all seven, whether the remaining drummers become NPCs, or if there's another intended approach.
Finally, I think the handwritten font fits the atmosphere really well for the titles, but I found it just a little difficult to read at times.
Have you had the chance to playtest it yet? I'd love to hear how a typical session unfolds. I think even a short example of play or an actual play would make it much easier to picture how everything comes together.