I think it’s entirely possible to keep them at the right pressure give or a take very little. The staff could just rotate ones that look squishier than others out with freshly filled ones.
But still, I’m sure we will see more than one instance of a grabber not working because a tube got flatter through the course of a match, maybe even unscorable after it’s been picked up. Imagine a manipulator made useless by a flattened tube than can’t be dropped by your bot.