Unverified trials are a deprecated method. They have documented flaws (see the page I linked to). One of the flaws you ran into. There is no way to make unverified trials “better”. Other than switching to verified trials, which fix the flaws of unverified trials (but also have their own tradeoffs; again, documented in the article I linked to).
I'm not brushing your request away. We've given this a lot of thought. We've designed both systems. And we've extensively documented the trade-offs between the systems. We also wrote it down in our documentation (hence the link). There's not a whole lot of use copying-and-pasting the exact same reasoning we already spent a lot of time designing, documenting, and editing, but just in a forum post.
Unverified trials are a dead-end technologically. They have their very limited use-cases. And they will get 0 of our development-time going forward.
Use verified trials.