Why do you need to this? Depending on why you need it there are several approaches you could take.
If you are stuck to the approach you are taking at the moment with running the call to get all the connected accounts, you likely could find issues as the client email address used in your Bubble application could be different from the one they used to create their Stripe account, so you could end up with no match.
Either way you need to look at the results of the API call which return a list of accounts…take that list and run a filter on it and filter by the email address.
Please provide a bit more details of why you need this and I could likely give a better approach.
Boston85719 is an expert Bubbler with a decade experience as an educator. Real name Matthew, he has been actively building SaaS apps, marketplace apps, scheduling apps and more for clients, himself and for sale as templates.
As an official Bubble Bootcamp Instructor, he leads Bubble Bootcamps on a regular basis.
Always willing to offer advice via the Bubble Forum, Matthew also offers Private Personal and Group Training Sessions.
Through his site, NoCodeTrainer, Matthew provides a range of tutorials with editor access to help you jumpstart your Bubble development.
Always accessible you can send Matthew a private message via the forum or send an email directly with your requests.
Be sure to checkout the Stripe Integration Course when you are ready to integrate Stripe payments to start monetizing your application via product sales or subscriptions.