PS: cerebellum segmentation is still unavailable on CAT software?
I believe it's now available. Here is an example of the output from the simnibs when cat is used
No, I think it is still not available in CAT12:
CAT12 - cerebellum extraction - #6 by Francois
How can I include the subject's cerebellum in the source analysis?
Process the MRI with FreeSurfer.
https://neuroimage.usc.edu/brainstorm/Tutorials/LabelFreeSurfer#Subcortical_structures:_aseg_atlas