So, is there a difference between Wanatoka Tanzania and Wametoka Tanzania?
"Wametoka" is past perfect. "Wanatoka" is present/present continuous. "They have come from" vs "they are coming from".
Wanatoka as in they are in the process of leaving right now or soon. Wametoka as in they've already left, so now we look at them as 'They are from'
That makes sense, but we've already learnt wanatoka to mean "they come from" with one's country of origin, and every phrasebook and introductory video for Swahili has ninatoka + country to say where you're from instead of nimetoka.