Well, the roof accessories work only on the roofs, right? However, being that the vaulted roof is made out of many flat roof planes, it is a question HOW will they work.
The Complex profile - if used with a wall tool - will "trim" another wall, provided their reference lines meet correctly, making a correct model, but it will still not be the roof.
The object can work, but then you are off on the SEO path which can be painful. Plus, it is zero thickness, so the SEOs will probably not work.
The vaulted roof is versatile ... it is a bit of a pain to adjust all the small bits to the curved plan of the gable, but it is manageable. Don't forget to CTRL click the joining edges of the ridge!
Djordje
ArchiCAD since 4.55 ... 1995
HP Omen