Don't treat this as an advice per se, because I'm in your shoes (also trying to progress from intermediate to advanced). However, this is my few cents.
BE EVEN BETTER VERSION OF YOURSELF
First, I think you need to trust yourself more now. You have already proven to yourself that you can do it. Most likely you have proven several times. You should trust your knowledge, your experience, your intuition (which as an intermediate you should already have some). Therefore, asking for reading/course resources as an intermediate is probably the wrong way. Most likely you have already studied extensively and are already familiar with majority if not all concepts. Remember, every master is different. And if you want to become one, you need to become a very good version of yourself. Ask yourself again what are your strengths, weaknesses and sticking points. And work on them consistently over long term. Do more of what works for you if you want more consistency, or work more on your weaknesses when you feel bored or want to increase breadth. You can become advanced either as a specialist (when you practice one type of game over and over, and become great or amazing at it), or as advanced generalist (when you are very good on some areas, and good or at least decent on others). This is a personal choice, not a question of good or bad decision.
THE HARD WAY
Action, action, action. This relates to the previous one in a major way. You already know many things and can do many things. Now, you have to keep doing them, in order to polish. Instead of chasing for a holy grail, the way to go is to make consistent small improvements over long period of time. It's like with foreign language acquisition. As a beginner you need teachers or some external resources, in order to learn grammar, some basic vocabulary, basic idioms, etc. Then you keep practicing what you can do by talking to others, reading, writing. Your vocabulary and ease of talking increases slowly over long term. Then you realize that you can communicate quite easily in many situations, but still making some mistakes here and there. It's good but it's not great. In order to progress to mastery, you just keep doing what you did in the past - talking to other people (from different background, accents, cultures), you read more advanced books or articles, so you keep expanding your vocabulary, and becoming more smooth, and more sophisticated. I believe, instead of looking for new resources, go back to the resources you already know. You already know which stuff is good, and which stuff is bad. Read the good ones again. You will remind yourself about the fundamentals (and it's really all about consistently improving fundamentals over long term). You will also, see the concepts/ideas/advice in new light, due to the experience and perspective you have now, and which you didn't have when you read them for the first time.
CONSULTING SPECIFIC, NICHE ISSUES WITH EXPERTS
This someone contradicts the first point, but not really. You need to learn to ask specific, niche questions, and you need to find people who can help you with these questions. And offer them something valuable for them in return. Most likely you won't find answers for these in books or courses (most of these are for beginner to intermediate level clientele). Well, you may find answers you seek in books/courses, but it's not really time efficient. They are sometimes burried deep, and it's gonna cost you time to find them. While beginners should read a lot, I believe as an intermediate you should practice a lot. Practice, review, improve, practice, repeat.
Good luck
