Slitherine

I guess it’s not possible to create new unit traits, is it?
I know traits with game mechanics will obviously not work without recoding the game, but I’m rather interested in creating description traits for units to add useful information like torpedo cooldown, range, and power, or how many carrier-based aircraft units this carrier can hold.

Not possible at the moment, no.

The things you mention should be listed in the UI of course, it's on our to-to list.

I'm glad to read that! I've improvised this by renaming units which includes the fuel and radar values next to torpedo data, as these can be important purchase/upgrade factors too - at least with my modified unit stats.