Would be great to use Scala 3 but I'm stuck with 2.12 because of AWS EMR.

I've been using Scala 3 on a personal project and it's nice that Enum's are finally worth using

The old implementation felt like a trap with it's downsides

(even newer here, hence a belated reply).
My interactive climate model SWIM now written in scala3 (originally java), uses loads of enums for real-world things, for example gases in the atmosphere, landuse biomes, sources of electricity, economic sectors, scenario definitions, stabilisation/equity algorithm options, etc. Such enums help map over irregular data structures, connect with user-adjustable choosers, etc.. So I waited for scala3 before embarking on this project - and am very happy with the language.

Recently I experiment applying enums also to region-definitions, but anticipating over 1000 of these, fear that the neater code may compromise efficiency (bearing in mind, this all works in scala.js - client side). From such experience, could elaborate (maybe elsewhere ...?) some ways Scala3 enums might still be improved.