The Eickhoff-Zilles 1.8 MPM atlas distributed with AFNI only has a few parts of the insula labeled (Ig1,Ig2, Id1), but surprisingly none covering the majority of the insula, while in their ML atlas for the N27 dataset, there is only the insula as a whole. The TT_desai_dd_mpm atlas and TT_desai_ddpmaps probabilstic atlas from Rutvik Desai and distributed with AFNI do have sub-divisions of the insula you might want to consider. Jurgen Mai's brain atlas has a large number of subdivisions for the insula that are well worth viewing, but that atlas is not yet available in a digital form. The Allen brain site includes three sub-divisions of the insula. You may be able to transform the atlas and corresponding single subject to Talairach space. The Brainnetome atlas provide six sub-divisions of the insula, and that atlas is downloadable and potentially useable in AFNI without too much effort, I think.

If you have an atlas in MNI space and a dataset aligned to the TT_N27 dataset, I would use the "adwarp" command, as mentioned in this previous thread.

https://afni.nimh.nih.gov/afni/community/board/read.php?1,155239,155244#msg-155244

The TT_N27 dataset itself was transformed manually from MNI space, and this would apply the same 12-piece transformation to the MNI space atlas.

One simple way to subdivide the insula is for you to do it yourself using a method like this one from another recent thread:

https://afni.nimh.nih.gov/afni/community/board/read.php?1,157456,157474#msg-157474

Also thanks for the new word for me - "ineluctability"! I have somehow *avoided* that word!