There is some small visual bug in the NPC actions tab. When I add there a spell and afterwards (not before) I change the misc. bonus of the DC (to 10 in the following example) then this bonus is not respected in the showing window of the save, but the save code itself is still respecting the bonus as you can see in the chat message (thence, automation still completely okay):

Changing e.g. the ability cycler button resets this behaviour such that the bonus will then be accounted also in the display.