> As previously discussed in some other bug report *vague hand wave*, it
> makes no sense to use regexps for outline in generated buffers.  The
> functions that generate the buffers knows what's a heading, and should
> mark the headings properly (with text properties), and
> outline-minor-mode should just react to these text properties in these
> buffers.

That was in https://debbugs.gnu.org/31094#40

Is this a promising direction?