I wouldn’t advise to give much importance to Finnish language. The most important part is to fulfill all requirements
So it wasn't like that the agent was interviewing me or evaluating my language skills
It's not an interview - don't believe anyone who tells you it is.
The migri "interviewer" asked me only one question (did I have my own company in the last 5 years), to which I replied no in Finnish.
After copying all my docs, he spoke for a couple of minutes - the main thing I picked up was it was going to take at least 9 months to get a result (in line with the website guidance).
The LAW says that citizenship can be obtained with a pass in the YKI combination you have. It is THE LAW.
The migri application says if you can't discuss in Finnish with their employees, it "may" affect your application. This is very vague, and I take it to mean they might somehow double check that it was you that actually took the exam.
My advice - stop worrying. Put the application in, go see them, manage the "interview" (it's not!), and then forget the whole thing, for 9-25 months.
Perfect mastering of the language is not expected with YKI 3.
She even tried to speak english but I was trying to keep Finnish LOL-). Do not worry it is not an exam.
She tried to use simple Finnish when communicating to me

In total this visit took about 10-15 minutes. There was no any complicated questions at all.
You should manage just fine in Finnish. The officer's questions are intended to verify information you have provided, so short answers will suffice. If ever you should stumble, I wouldn't worry. After all, the officers understand that contacts with officials are not an everyday experience, so they get it that people may be nervous. You'll ace it

They won't intentionally try and derail things or confuse you though but they will ask you general questions.