On any particular side there are two lines that connect to each number. But you follow the line alighted with the number on that axis towards whatever point inside the triangle.
Go from the axis to the point instead of the point to the axis.
Although, you can still figure out which line is for which axis based off the angle of the number.
For example, the numbers for clay are horizontal and are associated with the horizontal lines.
My guess is that the game gets really repative because that is kinda the Tyranid style. Waves and waves of teeth and claws. Maybe some variations, but how long can you send swarms of the same guy before its boring.
I guess Vermintide and 40k version (can’t remember name) make it work but they are very different games.