Even a girl says she is fluent in English. There is a chance that she does not fully understand you when you meet.
I think it is good to video or audio call before you arrive to see how communication is between you. Just basic sentences or a few words and a wave.
The English taught in Ukraine is different to that of native English speakers in their day to day lives. They are not ready to talk to a foreigner and don’t understand all they say at first. With the native speaker having any kind of accent it would cause more difficulties. Most girls in Russia and Ukraine do not know there are different types of accents in one country.
Some types of accents in UK, (especially Scottish) would be the most difficult for them. The American accent is the easiest for them to understand and most know American English.
There is a chance that you are the first foreigner that she has met. She will assume that you will speak a certain way, an American accent or London accent. It’s possible that when you speak she might say you are not from your country and think about rejecting you, especially is you do not look typical for that country.
If you are a non-native English speaker, she may not understand you too. Maybe a translator will be needed to start with.
To speak slower and clearer will help. Generally it’s fine speaking slowly to a girls it’s not seen as demeaning (like speaking slowly to a child)
At school she would have learned English. All girls will know a little English. Any girl not experienced in English will not talk in English as they will be concerned about making mistakes.
I think before visiting it’s best to ask what the girl prefers, a translator or not. Some like a translator as it makes them feel more comfortable. Some don’t like a translator as the don’t like someone else knowing their business.
I have had times when I have met a girl and have not been able to communicate to each other in any way at all, even apps. For me it’s a funny situation together, this is ok. For the girl it might be funny or they might think it’s not possible to communicate that is it, and you will be rejected. At least it’s a good test to see how you interact together.
I think that if there was a connection between a man and a woman the language is not so important. They can go places together, most communication is non verbal and language between them will develop.
For me I think, it doesn’t matter if a translator is used or not.
I prefer not to use a translator, I have used a translator and found that after a couple of dates she wasn’t needed. There was an anticipation that while the translator / chaperone was there, nothing romantically happen. Then things can get romantic.
Probably more important than the translation the woman gives is the guidance of how she feels about the woman, what she has said. A woman of a similar age to her mum good.