This NPC pack is super cool! I really enjoy Celeste (although it is very frustrating at times), so having a feature based off of it in one of my other favorite games is awesome! Who knows, maybe someday someone will make an entire Celeste-based level in SMBX2?
I do, however, have a pretty minor- although very annoying- bug to report. There seems to be some incompatibility between this NPC pack, and rooms.lua by MrDoubleA. Specifically, when a player enters a red bubble, and uses it to exit a room, the orb is destroyed, and the player regains control as they normally would when one dies, but the sounds don't stop looping! If the player then does the same thing again, the sounds will loop on top of one another, which is not exactly pleasant to the ears. Additionally, if a room is exited and subsequently entered in rapid succession, the initial orb will be cloned because rooms.lua and the orb's code both try to respawn it at around the same time. From my experimentation, this seems to cause both orbs to react to each other, and both explode as soon as the player tries to use either one.
Even despite this incompatibility, I really enjoy the red orbs! They're super fun to just mess around with, even if they don't work with the Celeste-styled rooms. I hope a fix is made sometime soon, but it's understandable if something like that just isn't possible!
(Also, my apologies for not discovering this sooner!
I just discovered a solution, which is to add the NPC ID of the red orbs(751 by default) to rooms.lua's npcRespawnExceptions list, which fixes both issues I was having!
Progress on my SMBX2 episode has slowed down due to real life things, but I can confirm that I have fully completed about three levels so far! Once I've got a few more levels completed, as well as fragments of others to showcase, then I'll possibly put together and release a trailer! I hope to have that out later this year! As the full SMBX 2.0 will likely change a lot of things, tho, I don't plan to release the full project until after that's come out. (...Plus I need WLDX loadability anyways)