Necessity of half-turn twists in the edgeless case

Determine whether every configuration accessible in the edgeless case using half-turn and quarter-turn basic twists is also accessible using quarter-turn and reverse-quarter-turn twists alone.

Background

For edged cubes, the paper proves that convergent sequences are twist-finite, so every half-turn can be replaced by two quarter-turns without affecting convergence. The analogous replacement property is not established for edgeless cubes, where convergence behaves differently and is not closed under concatenation.

References

In the edged case, since a basic sequence is convergent if and only if it is twist-finite, there is no need for half-turn twists, they can all be replaced by two quarter-turn twists without affecting convergence. Is the same true in the edgeless case or are there configurations accessible only using both half-turn and quarter-turn twists?

Solving infinitary Rubik's cubes  (2502.01650 - Tisdell, 30 Jan 2025) in Section 7, Open questions, item 4