> Arch are just curves extrude + sculpt with bolleans function
> Only "text" were import from rhino 3D

Does he have the original curves before they were extruded?

If I can get the original curves that were used to create the extrusions, then I might be able to repeat the boolean and see what is happening that causes the loops. It is hard to try and figure out what caused the loops by just looking at the final result.

- Michael