Ulyana-Khrystyna is lovely! It's a lot of syllables but they are delightful syllables.
I don't personally much like
Nikol. Possibly partially because when I first came across this name, it took me a while to figure out it was a name. The story is that I kept hearing it over the headphones at work but in Polish accent it didn't sound quite right (stress on the first syllable). I kept wondering if this was maybe an abbreviation that I wasn't familiar with or kept mishearing. It took me a good few days before it clicked that it was just the name of a foreign girl named
Nikol. So just for the frustration it gave me, I don't like it. To me it's either
Nikola or
Nicole with accent on the last syllable.
https://www.behindthename.com/pnl/109883