I have an autonomous that scores two triballs in the Blue goal, as a Blue robot. The game manual shows this diagram in SG10 as an example of robots legally interacting in the Neutral Zone:
Based on this diagram, it seems legal to grab the triballs on the double white line, since when you have posession of a triball, it is technically an extension of your robot and contacts the other side of the Autonomous Line. So TL;DR: Can a robot grab a triball on the Autonomous Line if the robot itself, not the triball it grabs, avoids contacting the field on the other side of the line?