Is this normal spell-casting ai behavior ?

[Chazar]

I also have the impression that the AI prefers to choose among the 5 selected spells. So I usually script my seraphs to "Quickness","False Horror","False Horror","False Horror" and then either "Orb Lightning" or "Frozen Heart".

I guess that having a spell scripted shifts the weights for AI spell choosing a bit. At least according to my experience - and I really like it that way. In fact I would prefer it if one could only encourage the AI to cast certain spells instead of specifying a specific order...