Do you really need to work with a zoom of 1600?
You can apply a smaller zoom by placing a zoom layer onto the stuff that needs the fine design. Later disable the zoom layer to let it be at its own size.
Certain type of layers (like Blur Layer) eats lots of memory when zoom in too much, which can cause stability problems.
Bad alloc are difficult to fix. It would need a global improvement in terms of memory handling because sometimes it is needed to render a huge canvas because some layer has its parameter that way. When you zoom in you cannot avoid the effect of a non visible layer due to its long distance effect and so the bad alloc is reached (not enough memory).
Try to work with lower quality possible (9) and see what happens. Alternatively increase the compression of the tracing image sequence to use less memory.
The image handling of Synfig is not good. It holds in memory the image of the sequence even it is not displayed. We need to do something with this some day.