Ok, so I didn't get a chance to look at this over the weekend; however, I am kinda looking at it now. When searching the issue tracker for random, I see someone created a repo that has the option to random knife. Now, im not super familiar with (like at all) with Sourcepwn, nor am I super sure if its random for each round. But, if its not, i might just need a check for newRound() or something and then make a randomKnife() call again.
But looking at closed issues, I see back in 2018 the owner of the weapons plugin that this server is using said "nope".