I don't follow you, ours detect the existence of scarabs just as quickly... triggers occur (in order) but all at once every 1/12 of a second.

In my system if there is no scarab there it still goes on to the next one.

Also: in your map you have 10 scarabs in each reaver, which counts towards the total scarab count, where there are like an extra (9x4) 36 scarabs. I checked.

In mine I did "Bring Scarabs To Location," you did "Command Scarabs."