> Ends in 'a' = female: a relatively safe assumption, as far as an assumption here can be safe, with no other context. A strong majority in many places will match that.

Which places? I guess I ask because your next sentence:

> Many of the exceptions will be obviously foreign names with traditional spelling

Which makes me wonder if you meant "US places", because I can think of a few male names, which maybe categorised as "foreign" if you're in the US, that end in "a".

e.g. Csaba (pronounced "Chubba") is a reasonably common Hungarian name.

And some not so "foreign" ones, albeit mostly with Biblical roots, like Joshua and Ezra.

Indo european languages mostly, probably