While looking around the underworks of Molag Mar, I was greeted by some error popups:

"Script Error: EXPRESSION in k7_aa_cultist_script" and "Right eval".

It's a quest-related script from Arcane Archery attached to an NPC located in the underworks.

Here's the content:

I can't quite tell what's wrong with it, but it does seem a bit short in many spots. Some assistance on the matter would be appreciated.

Technically it should work, so first you should confirm that there is a journal named "k7_aa_ottis".

Then you might try coding a little more carefully:

Begin k7_aa_cultist_script if ( GetDisabled == 0 )            if ( ( Journal "k7_aa_ottis" ) < 2 )                        Disable            endifelse ; disabled            if ( ( Journal "k7_aa_ottis" ) >= 2 )                        Enable            endifendif End

If that does not work, clean the script entirely out of the mod and rewrite it (do not cut and paste) completely.

Yep, found it. Same spelling too.

I'll make a quick backup of the mod, change the script to your version (no cut & paste) and test it.

Thanks, Cyrano.

Conclusion:

Replacing the script didn't work, but cleaning it out and rewriting it from scratch did. No more error popup, with an existing save or a brand new character. I'll have to play through the quest itself when my other character reaches that point in the faction, just to be sure. But for now, yay!