I don't know what exactly you want to do in your microflow, but in general you'd place actions that should only trigger on a successful commit (i.e. no validation errors) as an after commit event on the entity.
I usually use custom exceptions (from 'community commons > misc > ThrowException'), since imho that is the most reliable way to make sure that you know that an object is not committed.
But you could also check if isNew($object) is true after the commit, which also indicates indirectly that the commit failed, or, if 'new' is not applicable in your case, check if object has changed since the last commit using community commons > ORM > objectHasChanged. The same behavior as in 'isNew' holds here.
I recommend however using exceptions, the hasChanges/ isNew approach is a bit of a work around, and more sensitive to future API changes.
If I remember correctly, the exceptions are visible in the log, even if you handle them, so thats a bit annoying.