Since the only thing changing is the culture ins the localization, I'd have the decision create a flag (such as set_character_flag = target_culture_lombard) for the culture you are converting to, then have the after section of the event clear all of the flags.
Next, create a custom localization that displays the culture name depending on the falg, like this:
Code:
defined_text = {
name = GetTargetCulture
text = {
localisation_key = lombard
trigger = {
has_character_flag = target_culture_lombard
}
}
# Repeat for each culture
}
Finally, have the localisation call your custom localisation when it needs the culture name (i.e. EVTDESCdawn.102;I have decided to convert to the [Root.GetTargetCulture] culture.)
It looks like you'll want a scripted trigger listing the conditions for building the trade post (for instance, the silk road's silk_road_trade_post_trigger is an or block listing all the provinces), then add that trigger to the potential block for your route's trade post in common/buildings. Additionally, you'll want the same conditions in your route's info in common/trade_routes under trade_post_display_trigger to make sure the icon displays.