one of the lacking feature in salome SMESH tools is better and more powerful mesh smoothers, specially considering that there is only the 2D version with the Laplacian and centroid algorithms. Mesquite is a sublibrary from trillions library https://trilinos.github.io/. It has been proven to be quiet powerful with parallel 3D smoothing, in FOAMExtend. a small presentation of mesquite can be find here:
Mesquite | Trilinos
As mentioned, Mesquite has an LGPL license which would enable the possibility of incorporating it to salome without licensing issues.