The team actively monitors Stack Overflow, so we prefer you post technical questions there using the tag #across.
More general questions or feature requests can be filed in the issue tracker as a Question issue type. The issue tracker is also the tool used for filing bug reports. You can find the issue tracker of a specific module on the module detail page.
There is also a Gitter channel where most of the core developers reside: https://gitter.im/thinking-across.
If you are looking for professional support, please see our support page.