Stable update: Sub-layers; New 3D effects; Timeline audio tracks & more.
It's still not clear to me from this why you can't just make changes in the editor. If you do that, then how it's saved on disk doesn't matter.
If a project fails to open for a missing sprite error, how else can I replace the missing sprite if it won't open in Construct?
If that isn't clear, I'm not sure how else I can explain it :/
That situation should never happen in the first place. If it does, please file an issue so we can fix it.