If you'd accept some criticism. Because there is one thing bugging me that many people seem to don't know or simply don't care(which is not the attitude you should have when you're an artist) . It's the "Cello"... It's WAY too big, a cello's body is really small, often smaller than a grown man's chest. The cello is not taller than the player if the player is standing up.
Of course there's an exception if the leg of the foot is longer, it doesn't necessarily mean the cello is taller than the player even with that feature. Why it's bugging me is because take away the bow, it's looks like she's playing a double bass (tbh, it looks like it even with the bow). Hope this was constructive feedback.
Well, fantasy/unreality has it's limits... Instruments will always have their defined looks and uses with certain features, not turned into entirely different instruments xD
Though when it comes to magical ponies, that's a whole other story because magic doesn't really have a true definition because everything or nothing can happen depending on each persons thinking and fantasy...
A cello has fixed definition, magical ponies cannot be fully defined