I lack a lot of knowledge in order to understand these mechanics:
don't tell me
everything I knows come from copying other modders' work or by a lot of trials and time spent...

"ancillary_triggers" and "ancillary_trigger_effects": should be autogenerated since it has those chance values. I met once one for general exp too (which is assigned in a similar way to ancs).
I think you can just not bother with them. DeI, for example, changed a lot of things into the anc script and it doesn't have those 2 tables.

So, no you won't need to add new entries into those tables

EditSF? For scripting?
Just copy/paste the script (from PFM/RPFM) into notepad++, make your changes and paste them into the mod pack.