I can't read your language and Russian language, but my assumption you guys are more active in Russian board, correct?
That's make @theymos think no need to create Ukrainian board because Russian board is already enough.
No offence, but considering the ongoing war russia started against Ukraine, I believe it is a little bit cruel to suppose that Ukrainian speaking users would want to write in russian board, communicate with local members and be cool with that.
The fact, that most Ukrainians know russian language does not mean that they would not like to have their own board where they can communicate in their own language.
In the first place you guys shouldn't have merged into Russian board knowing some day you would be requesting for your own Ukrainian board. Having Ukrainian participating actively in Russia local board eliminates any need to create a Ukraine owned local board.
Like what is the possibility that if given the board at this moment that almost all Ukrainians actively participating in Russia board instead of your local thread would wanna resort to using the local board when currently they aren't showing convincing participation in your local thread but rather flooding that of Russia. Have you considered the activeness of Pakistans in their local thread and others compared to that of Ukraine but are yet to have a local child board of theirs.
Am not against anyone requesting for a local board but from your statement it's obvious your idea was borne out due to the ongoing war between the two warring countries. And we're hopeful this war is going to end very soon for normalcy to take it's course. But then the war shouldn't be a locus point why you should be demanding a local board of yours. When the timing is ripe am sure @Theymos in his discretion would definitely see to it's ratification.