As far as I'm aware the BPMN standard does allow this, and you can find various resources on the net which show Receive tasks with timer boundary events.
Two Step Escalation: Solution 2 has a timer boundary event
https://camunda.org/bpmn/examples/
It's such a natural expression of how to handle waiting for a message which never arrives or fails to arrive within a timeframe.
also affects 7.4.3 and above that I've noticed.
regards
I can confirm the limitation but as Bonita BPM support a sub part of BPMN 2.0 standard this will be handle as an improvement and not a bug.