In order to pass information from an idea to a feature, you need to create identical fields on both, It would be a great feature to allow the user to select at the time of field creation on the idea to have it automatically created on the feature as well.
Thank you for your idea. As noted in the idea it is possible to carry over values from ideas to features upon creation. This article explains how to set this up in more detail.
Given the added complexity that would be needed when setting up custom fields, and low historical support for this idea, we are unlikely to implement a way to automatically create fields on both ideas and features simultaneously. We hope you can understand.