I think that “Exercises for Programmers” is a really great book for any language: https://pragprog.com/book/bhwb/exercises-for-programmers If you follow through that whole book using Ember, and you really stretch and try to do new things - you may find yourself learning a bunch of stuff. It sounds like you already know some CRUD, but you don’t say exactly what that mean - and how complex the relationships and the data you’re using is. This cookbook is fun to leaf through and try the things you haven’t done yet: https://www.packtpub.com/web-development/emberjs-cookbook
You basically just need a project, and new features will pop-up that you don’t know how to deal with - and it will force you to learn more. Many of the books are outdated or they are about a specific use for Ember. I though Jeffrey from https://www.emberscreencasts.com/ did a great job with emberschool: http://bit.ly/2e2oyG7 and although you may know some rails/ember crud - this course works with firebase which is really cool for MVP and early phases and it puts you in a place where you can really start challenging yourself.
Emberigniter https://emberigniter.com/ is always great. The global meetup https://vimeo.com/globalembermeetup videos should get you interested in some unique areas. Prototypal https://www.prototypal.io/ has some advanced programs / I’d sign up for front-end masters and take Mike Norths course - and then you can attend the advanced course that is in early December as part of your membership: https://frontendmasters.com - I have the rock-and-roll Ember book, but I never got through it, so I can’t say how that is.
The book “Deliver audacious web apps with Ember 2” https://pragprog.com/book/mwjsember/deliver-audacious-web-apps-with-ember-2 was pretty great. It was an ever-note clone - which I thought was more useful that CRUD blog in explaining relationships etc. however, it’s a little dated and uses mocks instead of something like ember-cli-mirage / BUT you could ignore the http-mocks and try to follow the book on your own terms. CodeMentor can be good for one on ones, if you find a good match. https://www.codementor.io/
I found I learned a lot more things when I just really dug into a project instead of generally just trying to learn everything about Ember. I think I wasted a lot of time on that / probably an entire year. Just build something that is a bit out of your league - and you’ll be forced to learn how to do it / and maybe there isn’t a way to do it yet - in which case you can lead the charge on that with thoughtful questions and real-world examples.
There are many things that Ember doesn’t do, or doesn’t do well - and figuring out a mobile-first native-feeling animation rich awesome website is still something that people are having a hard time with. We could use your help creating things that deal with truths like these: http://blog.runspired.com/2016/03/18/a-tale-of-two-states/
Local meetups are great, and pair-programming seems to be very effective. If you’d ever like to screen-hero and chat - I’d be open to that. : ) I’ve been trying to track down the best path for teaching and learning Ember for a few years - and I think that the guides and the resources are really growing to meet the demand.
Last thought, maybe you already know enough about Ember - in which case, there are a ton of really ugly website - and so learning CSS seems to be the most in demand. ; )