This hits upon an issue that's specific to this file; normally we save all files directly to the app build so that when they're accessed later we know we always get the same file, even if the commcare-hq code has changed in the meantime. That's impractical for this case because we're going to be zipping all multimedia into the file, which would be really expensive storage wise.

I think the best solution is to save the file pre-multimedia zip like we do with other artifacts, and then unzip and add multimedia just-in-time. You can grab me to discuss, I think I have a pretty good idea of how to do that.