If you are referring to the Actor field, an error message should be generated if the referenced record isn't an npc, or a creature. Otherwise, its a bug.1. The verifier for the Topic Infos table doesn't check if the NPC assigned to a record exists. I don't know if that is beyond the purpose of that particular verifier but it seems that error isn't catched anywhere else.
I'll mention this just in case because I can't reproduce the issue. The journal and topic error messages are sort of hidden at the end of the list beneath the script verifier output. Unfortunately, no sorting or filtering is implemented at the moment.
Is it illegal to have a negative quest index? It certainly goes against convention, but does it break the game? If so, then it was overlooked. The Journal verifier will check for duplicated journal indices, multiple quests with a named status, a missing description, and journal stubs without infos.2. How am I supposed to check the Journal Infos table verifier's functionality? I tried a negative Quest Index but that didn't result in an error message.