The xowiki::Objects behave per default the way you want (see below). On the source level the parameter render_adp can be used to control the substitution behavior. ::xowiki::PlainPage has set render_adp to 0, ::xowiki::Object inherits from this.
See: Class Hierarchy of ::xowiki::Object
in xowiki 0.106.3 it seems to me that
it shuld be parameter do_substitutions (not rendere_adp),
and I managed to change it by:
[my info parent] do_substitutions 1
before proc content