This should work:

[code] province_event = { id = flavor_der.3 title = "flavor_der.EVTNAME3" desc = "flavor_der.EVTDESC3" picture = SCHLES_eventPicture

trigger = {
    NOT = { has_country_flag = DER_had_event_3 }
    tag = DER
    is_year = 1600
    AND = { 
        owns = 263 #Ratibor
        owns = 264 #Breslau
    }
    OR = {
        primary_culture = hannoverian
        primary_culture = pommeranian
        primary_culture = hessian
        primary_culture = saxon
        primary_culture = bavarian
        primary_culture = prussian
        primary_culture = rheinlaender
        primary_culture = austrian
    }
}

mean_time_to_happen = {
    years = 200

    modifier = {
        factor = 0.8
        tag = PRU 
    }
    modifier = {
        factor = 0.5
         tag = DER 
    }
    modifier = {
        factor = 0.9
        NOT = { exists = POL }
    }
    modifier = {
        factor = 0.9
        NOT = { exists = BOH }
    }
    modifier = {
        factor = 0.9
        has_idea_group = humanist_ideas
    }
    modifier = {
        factor = 0.75
        NOT = { 1680 }
    }
    modifier = {
        factor = 0.85
        NOT = { 1700 }
    }
    modifier = {
        factor = 0.8
        is_year = 1760
    }
    modifier = {
        factor = 0.85
        is_year = 1780
    }
    modifier = {
        factor = 0.7
        is_year = 1800
    }
}


immediate = {
    hidden_effect = {
        set_country_flag = DER_had_event_3
    }
}

option = {
    name = "flavor_der.EVTOPTA3"

    every_owned_province = {
        limit = {
            OR = {  
                province_id = 263
                province_id = 264
            }
        }
        change_culture = german_silesia 
    }

    ai_chance = { 
        factor = 100
    }
}

} [/code