!Hey there and very warm welcome to the community of Spotify!
I'm really happy to hear that you're choosed Spotify for your lovely music listening need. It's great choose and I promise, you will be happy with Spotify 🙂
Let me help with your query.
There is no way to see all Offlined tracks, but you can add them to playlist using your PC and after that you should have all Offlined tracks. Remember, even if tracks are in many playlist, they count itself only once (if same track ID).
Worth to try 😉
And yes, if you have more questions or need answers for anything about Spotify, just ask. I'm here to help you with all questions and possible issues!