might be a dumb question but can a script that creates a JE that posts against a summary account?

I don't think you can post to summary accounts, script wouldnt change that

Agreed. Can't post against a summary account - however you can make an account a parent account without checking the summary account checkbox

Thanks, I thought so. Just needed confirmation. I'm trying to allocate revenue (referring to that summary account) from parent subsidiary to multiple child subsidiaries by creating JEs. Any advice?

it sounds like there was stuff posted to it before it was made summary? in that case you'd need to temporarily mark it as not summary to post your JE to move it out of that account, and then re-check the summary checkbox so no one can post to it again in the future.