Hi Camilo,
Currently we don’t have support to render custom fields in general tab in ej2 Gannt. However, we achieved this support by work-around solution using actionBegin and actionComplete event.
Please find the below sample link.
We have logged documentation task for this. The document will get refreshed in live by May 6, 2020.
Please let us know if you need further details on this.
Regards,
Logeswari G