I have a kind of similar situation as I have 3 names and one surname but since birth I have always used and been called onky with my first name and surname, the 2 other names being useful to distinguish me from homonyms. Having moved to Spain, most entities (state, banks, insurances...) insist on moving my last name as a first surname. And many people call me using my second name and third name, including at work. It always sounds so strange to me and it takes me time to realise people are adressing me.
Example (not my real names):
born as Alexander William Harry Smith, and having been called Alexander Smith all my life, people here in Spain unilaterally decide to call me William Harry or Don Harry all the time.
Thanksfully I have no need nor plan to apply for citizenship.