Roma should exploit that, it is not like Brighton has a good goalscoring record in Europe either. If they managed to win it with a slight margin that should give them enough confidence to continue pressing Brighton and force another error. According to WhoScored, Brighton is weak in defending counter attacks and a lot of their players make mistakes on a match, so it should be doable as long as the press it there. CMIIW.
The main weakness of brighton is playing opening against its opponent and very often doing back pass which can be intercepted by its opponent. The gameplay of brighton never changed and i was rarely seeing this club used defensive strategy. Playing openly put the defense into the big risk caused by many players were going upfront.
Brighton's strategy to isolate its opponent but it will not work when it faced a club which is strong in all of lines. This is why brighton was always struggling in beat the low block club which was often playing at the penalty box by putting as many people as possible to keep the goal keeper being threatened by its opponent.
It was very easy to identify the main weakness from brighton. Roma needs only to play low block combined with quick counter attack. Zerbi was a typical lazy coach and he keeps repeat the same strategy anytime. Roma was equal to the brighton. Rossi must tell his players to play lowblock.