Here is a first-pass attempt:
And here is the patch that you can have a play with.
After testing it out a bit, it seems it might be too temporary to notice when actually animating and focussing on the core content in the center of the view (as seen in the videos). I had originally thought that it would only really be necessary to show this during transform time, since this is when most transforms are likely to happen. So, if you were in fact making a series of edits, after it while you might start noticing the flashing and/or be able take corrective actions if necessary. However, on second though, this may still cause some unexpected keys to be set if using the clear transform tools, or other posing tools which don't have a modal loop.
Therefore, it might be necessary to keep a warning text in the corner where it now appears in this mockup under standard conditions, though without the border or icon, and probably not in red (no error here?). Something like: