Hey, thanks for the feedback! I'll try to take some time to look into those issues.
Edit: looks like the first issue is on Unity's end (the canvas does in fact resize, but Unity's not updating till it's been focused). RE the auto-detect size, I spent a bit of time tinkering to see if I could figure out where they're pulling the size from without success; I've submitted a feature request on itch.io's github about it though, and will update this if more info on the auto-detect becomes available.