Thanks for the detailed report!
I'll try resolving the low byte operator- and overflow issue at my earliest convenience.
Animation data was originally not intended to be included with single metasprites as the animation scheme is considered "opt in" and a lot of projects out there assume their own scheme, but i can see if i can include some kind of setting for that where it makes sense. That might take a while longer.
196 days ago(+1)
Once i'm done with the next release, you'll find the temporary settings here:
And the permanent (startup) counterpart will be found in the Preferences; text export tab: