Why is there no gender selection for my language pair?

Let us clarify a little regarding selecting genders for your desired languages.

We don't have voice output for Ukrainian or Croatian (let us know if you come across others so we can verify). The language/gender config is meant to map to the people in the conversation.

In other words, if I were talking to a female Spanish (Mexican) speaker, I would select male / English / US and female / Spanish / Mexico. The app would then translate my voice into Spanish and speak it out in a male Spanish voice, and the female Spanish speaker's voice would be translated to English and spoken aloud in a female English voice.

So, in the case of Ukrainian and Croatian, there is no need to map the gender for the English speaker since it there is no voice output in either.

Not exactly the answer you were looking for, but I hope it helps.