3 ilutrações recusadas por problemas técnicos

Did you scan these images before uploading them? I suspect the scanning quality wasn't that good, hence the 'technical issues' rejection; it seems to have resulted in artifacts in the scanned copies.

The first one is not sharp and exposes aliasing:

(This is seen at 100 %). I think you have blown up the resolution.

The third one  may well be only reduced pictures of the submitted ones, as it is smaller than the two others.

For the black/and white one, I would need to speculate. There are some drawing errors in Fingers, eyes, but if it has been refused because of that, I can't tell. It may also have got because it's monochrome. That would have been a false refusal in this case.