Problem with picking points

[piesdescalzos]

Hello Everyone! I'm having trouble picking points. My blender version is 3.2.2 and using the master branch of the addon.
The ICP works fine by clicking "ICP align" several times (didn't touch any setting, leaved everything default.) in a Suzanne monkey with 3 subdividions, even though this is ideal and not the real-world use that one intends to use the addon for.
I'm not sure how the add-on particularly works. (I've watched the YT videos and have a basic understanding.), but I believe that the "picked points" tool is very important for dental work. In my case for a fusion of a high-res 3D scanned denture into a low-res CBCT denture. Where I have a whole CBCT skull and a small scanned dental cast.
Weight paint seems to work "fine" btw, or at least it doesn't throw any error. (So, not sure it's doing its work)
Does the "picked points" just make things faster (at least avoids crashes?) or more accurate? What's its purpose? What happens if I don't use weight paint in a situation that deserves it (like in the patmo141 YT video?) What does the alignment method do? So far, without the picked points the only results I get are either an averaging of position between two objects or a crash.

This happens when I click "Align: Picked Points":

On a side note, when I click "ICP Align Redraw" there's also an error (just reporting it, don't know how it differs from "ICP align")
.