This is really exciting- thanks for breaking down the Aettir and explaining them so thoroughly, @Liisa! 
For some reason, reading about the different Aettir reminds me of the steps towards writing a story! 
Freyr’s Aett is the most basic bottom level, the outline of the book. This level deals with setting the stage- exploring basic needs for a healthy physical and spiritual life. It’s like the development of the overall theme and character details.
the next level is Hagal’s Aett- the challenges along the road. The plot, the obstacles that we face along our journey. This is the excitement- the quests, the climax, the things that make life challenging but also worth living.
Finally, Tyr’s Aett is the unseen magic that ties everything together. It’s emotion, result, forces beyond our power such a fate and the deities. This is the gamble of publishing a book, the unpredictability of the audience 
I loved learning about the Three Aettir- thanks again for sharing your rune wisdom, Liisa! 