Looks like it was a typo, here's a fixed PRU event if you want to fix it yourself, or I'll have a fixed mod uploaded in a minute.
Code:
################################################## #######################
# Austria claims the Rhineland # by Darkrenown
################################################## #######################
event = {
id = 70123
random = no
country = PRU
# triggered by AUS 70122
name = "Austria claims the Rhineland"
desc = "Austria has beaten us once, we cannot afford to lose this war. But can we win it?"
style = 0
action_a = {
name = "Give up the Rhineland"
command = { type = prestige value = -50 }
command = { type = secedestate which = AUS value = 778 when = 0 }
ai_chance = 70
}
action_b = {
name = "Refuse!"
command = { type = prestige value = 50 }
command = { type = trigger which = 70124 } #AUS
ai_chance = 30
}
}