I don't know much about xfdocs, but according to documentation these are the only size-related options supported:
- FillMode Options: Width, Height, LargestSide, SmallestSide
- Anchor Options: BottomCenter/Left/Right, MiddleCenter/Left/Right, TopCenter/Left/Right
- Cropping Options: This allows a user to narrow in on a portion of the image before other settings are applied. The default setting is 0 which means cropping is not being used.
CropLeft, CropTop, CropWidth, CropHeight
Note the bold bit: if you crop, your image will be cut before any other operation happens. If you're not seeing the entire chart, the first thing to do is getting rid of the cropping options, because they are not meant to resize but to chop.
Next, you can try to play around with the FillMode options, which are the ones meant to resize stuff. If they are not enough, you'll have to talk to Support or file a proposal on IdeaStream.
To be honest, it's hard to do advanced layouting with macros... One (untested) idea could be to try and constrain those images on the Powerpoint side instead, with very rigid containers.