I would like to be able to submit a feature request to A12. How and where can I do that?
All colleagues are invited to communicate requirements for A12.
First, please talk to your TPS or BPS contact to clarify, if there is already a similar feature or a working workaround or a project-specific solution. To ask questions here in discourse is also always a good idea. 
If you want to file a requirement ticket for A12, you can use the template (<INTERNAL_LINK>) and follow the instructions in there to have a nice requirement, which is clear to your colleagues.