I love the flavor of this subclass! If I was playing a rogue right now, I’d probably ask the DM to try this one out.

I would recommend a few changes to straighten up some rule interactions.

• I suggest moving the info about the spirit raven form, from 13th level Raven Shape to 3rd level Opportune Transformation. This would clear up some edge cases, for example: what happens if I use Dash, turn into a raven, and fly into a wall of fire or trigger an opportunity attack? Do I use my stats, or the raven’s? Does the Raven take the damage or the character?
• Speaking of which, where do I find the stat block of the spirit raven? “See its stat block in the PHB/MM/Mordenkainen/whatever” would really help.
• Sixth Sense is fine but a bit wonky in practice, as the game doesn’t distinguish between 2, 3 or 4 hours. You either have effects lasting 1 hour (which usually translates to, until your next short rest) or 8 (which translates to, until your next long rest). Sixth sense stays active a number of hours equal to your proficiency, which would be confusing to use in practice. Nobody is keeping track of the time with that much granularity. I’d suggest having it last 1 hour. If you want scaling, you could provide a second use of it at higher levels.