I would go with continents but the reality is that Scala presence is not that equally distributed across the globe. I think we can split by language / "regions".
For example:
North America but only Canada and the USA (English)
Mexico, central America, the Caribbean and south America (mostly Spanish)
In Europe... We have to many languages but also lots of representation of community. I don't know how to do it here.
New Zealand + Australia
Pacific Asia (Japan, Korea, China, Taiwan, Philippines, Singapore, etc.)
The list isn't long enough for it to matter yet, but before long it will matter
I think we could start by splitting it out by continent, and then if the list gets really long consider further subdivisions (e.g. by region)