Unfortunately, Penta does not support HBCI. The main reason for that is that the HBCI technology is outdated and will be replaced by a new standard very soon. Penta will support the new standard.
We are now working on an alternative for HBCI that will enable a seamless integration to accounting and tax tools. This state of the art API will be delivered in the next 3-6 months.
Please check out our product roadmap to see the most up-to-date information on when this feature is coming. You can also vote for it right on the roadmap and we will try to make it happen sooner.