But there is still a (red) link to Definition on the subpages template (between Talk and Related Articles)
if there is no definition (and no link, if there is a definition).
To me who sees red links as an invitation to contribute, that is a feature, not a bug.
I have 2-3 reasons for suspecting a bug:
* The link to the definition is only shown when there is no definition - it vanishes when a definition exists.
* On the talk page it is shown three times that there is no definition: red link, in the template, and by an infobox. An overkill, I think.
* Though I could not swear to it: I am quite sure that this red link started to appear only recently.
To me, all this indicates that the link to the definition is not intended and therefore a bug (even if it might be useful).
(CZ is not so far as TeX that a yet undiscovered bug might become a feature

The subpages template (at least on the main page) is intended for the reader, not for the author.
Therefore I think that red links should rather be avoided.