I'm in Canada. My parents were Ukrainian immigrants. We always spoke fluent Ukrainian at home. :) We never used 'інколи' for 'sometimes' - we used 'часом'. Of course there's nothing wrong with learning new words & increasing one's vocab. (That's what I'm doing here.) :) Thanks for your observation. I appreciate it. :)
They are not completely interchangeable. You can ask Ти часом не москаль? Aren't you a muscovite? But in the duo example інколи is ok.
This is the first time I've heard the word 'інколи' used for 'sometimes'. We've always used 'часом' (or 'часами') for 'sometimes' in our family. What region/ country does 'інколи' come from?
It seems, you don't live in Ukraine, do you? Інколи is a literary word. I mean, a word from the Ukrainian literary standard language.
It sounds like it's analogous to Russian когда "when" (Ukrainian коли) and иногда "sometimes" (Ukrainian інколи).