We try to follow commonmark and they haven’t accepted this extension yet.
Regardless, at a certain point there will be a a major rework of the the parser libraries we use (both first party and third parties). At that time, we will look into definition lists.
There are no ETAs on when this will happen and this is not short term task. I am sorry.
I think the use case present in this FR can be resolved with the even more powerful implementation of Native support for Inline attributes