With 8 teams there are only 7 possible opponents, so playing 8 events against different opponents cannot work. The best solution is to drop down to 7 events and 7 rounds, then all 8 teams can play each other exactly once. For example:
(---) (H D) (A G) (---) (E B) (F C) (---)
(D B) (---) (C H) (---) (---) (E A) (G F)
(E F) (G B) (---) (---) (A H) (---) (C D)
(---) (E C) (---) (H F) (---) (D G) (B A)
(---) (---) (F B) (A D) (G C) (---) (E H)
(C A) (---) (---) (E G) (D F) (B H) (---)
(H G) (F A) (E D) (B C) (---) (---) (---)
It's symmetric, so it doesn't matter which way around rows and columns are assigned to rounds and events. If you must have 8 teams and 8 events, then it is possible to make a similar schedule, however each team will have one other team that they play against twice. I can make this if you would like.