Pseudo 8R at steady state.

A chamber-and-flow-friendly triplex (i.e. no big swings, fancy partial triplex molecule storage, or molecule entering and exiting the glyph from the same direction) would be the one here with 4R and follow a strict enter/exit - pivot - handoff - pivot cadence, especially that two fire atoms has to enter the glyph at the same time. It also means that handling a pivot needs at least 5 instructions and in a pseudo 8R tape the four pivots has to be handled by four different arms.

With the part from triplex laid out and dispersal glyph laid out, the duplication process is mostly opportunistic. Arm 6 is in a good place to swing two fire atoms (that is to be pivoted away) to triplex glyph, but the second swing (earth) would collide with two atoms (air of same batch and water of next batch) at the same time. And then the great save comes to arm 1. It has opportunistic timing, opportunistic geometry that swinging the other way avoids both collisions, and opportunistic instruction tray that arm 1 has the space aside quint dispersing and that there's exactly one cycle of extra time quint dispersing can move earlier and not collide with previous batch's earth.