What format are comment FrameOffsetRegion width/height in?

I’m trying to reconstruct a comment region so that I can save a screenshot of the highlighted area. For that, I would assume that region_width and region_height give me the pixel size of the region. However, it seems like they are in canvas coordinates, but when I move the frame the comment points to on the canvas, region_width and region_height never update when retrieving comments via the API, which would mean they are relative to the frame? But in that case, their dimensions are way larger than the actual frame size.