I've been tracking Galuf actually since Night 1 if he would strike again. For some reason, I didn't get a result on Night 2, but it turned out I did get one on the night he was killed, surprisingly. He targeted Cid.
I just realized that Faris did not see what Galuf did on night 2 and the reason was more than likely because the Mafia made an effort to role block him so they could poison Noctis unhindered. It takes 2 days for the poison to kick in and the person dies on the 2nd night meaning that since last night was night 4 then 2 nights before that was night 2. Cid is still in danger because he was visited by Galuf on night 3 and tonight will be 2 nights later as it will be night 5.
That doesn't work because according to Faris, Galuf targeted Quistis on night 1, and she died on night 2. So that's one day to take effect. Noctis more likely died by a Mafia Ninja. Since we have a Tracker in play, a Ninja makes sense since they can't be tracked.