In AW and DW Experience is solely used to level up, although in several DW hacks (Homebrew World, for example), Experience can be used for other things, for example, to gain advantage.
Your reasoning sort of makes sense to me. It still seems like a bit of a stretch to use “expedience” to describe the things its describing, especially in the way “expedience” is commonly used in English.
I guess my main worry about the word is that it sticks out as going against one of the three main goals of Fantasy World: to be “Accessible.” “Experience” is an accessible mechanic that has near cultural ubiquity, and is easy to grasp for many players (i.e. the more you play, the more experience you have playing). Expedience is clever, but it makes the players do small mental gymnastics to get to the meaning you want to convey.
I really love how accessible and practical the rest of Fantasy World is! This one name just stood out to me.
Thanks for your replies! :)