Is it possible to use the number of form submissions as A/B Test conversion goal?
You can create a custom KPI, you can find an example here
There are few form events for submission you can find them here
You can attach on a specific event in the EvaluateProxyEvent method, then in Evaluate, you can check if your conditions are met and return the appropriate IKpiResult.
Hi I wrote a "Submitted Form" example KPI here: https://github.com/episerver/AlloyDemoKit/blob/master/src/AlloyDemoKit/Business/FormKPI/FilledInFormKpi.cs