City and province names

I want to change the names of some provinces (and its capital city or caste). But I could not find the right way to do this. Please help me, what file do I have to modify, and what will be the solution?
( For example I want to change Budapest Province to Buda Province, and its capital should be called Buda!...Because in the Medieval Hungarian Kingdom Buda, and Pest were two different cities near the bank of Danube opposite of each other..so I want to mend the historical reallity)

It's in data/text/imperial_campaign_regions_and_settlement_names.txt
You'll have to convert the strings.bin files to edit it first, though

Thanks for help!

To change the City/Castle name is posible even IN the game. It is in the menu for City/Castle details.