I need to crop /trim away any white space around text in a PDF file and I need access to some simple data contained in PDF annotations.

My working solution using pdf.js is too slow for my use case. Mutool seems to be much faster, but I face 3 difficulties:

1. In mutool run Javascript I see no documentation for accessing annotation objects.
2. In mutool run Javascript I fail to do some reasonable cropping /trimming of the image. I succeed getting the bounding box using their example with a virtual interface.
3. It looks like the transform matrix for rendering a pixmap is ignored - I get images with bad resolution.

Any experience with mutool run Javascript access to PDF files out there?