I just noticed that if you close Cleanmgr+ and launch it again that the +more items are remembered. That makes the situation better. So, apparently, once you run the "Check installed scripts" under the +, the ones that are found are remembered unless/until you run the "Check installed scripts" again. That is good.
Initially, how to get the +more items to have the "space to gain" calculated is still not intuitive. That is still a hurdle I think you need to address.
Maybe the option under the + should say:
"Check which +more scripts are installed"
"Check which +more scripts your Windows account is using"
See my message below for other thoughts.