Screen Customisation - invisible parts

I wanted to add two fields for personnalized activity type "Training", in a dedicated section in "Activities" screen.

Section Formation
field 1 
field 2

With screen customisation plug-in, I have first added the fields (section + 2 fields) after another section "to do list" ("Points à traiter" in French). 
But the part (a table) that is after "to do list" section is invisible through this plugin. And when I moved my "Training" section,
then the to do list table came with it. (see attached screenshot)

Now I don't know how to put the table back in the to do list section. Could you please help me ?

Thanks for your help