Unless I managed to misapprehend a rule that worked, it is much, much simpler than that! Level 27 is the place you can start to understand it properly, as the symbol can see two cardinal directions (the previous two levels that introduce it restrict the symbol to one direction)
I've rot13'd a very light clue below:
guvax bs gur e naq gur rdhnyf nf vzcbfvat n erdhverzrag ba gur yvarf gung gurl pna frr (qba'g sbetrg gurl pna frr guebhtu jnyyf).