Thank you for asking this question. I'm far from an expert in the English language and admit that I have not consulted a dictionary before using the word "substantive" or, now, before attempting to state my perception of the words "substantive" and "substantial".
I intended the word "substantive" to indicate a change in meaning, whether by addition, change, or removal. To me, adding a profile to the Black Sheep project is in this category. When you also used the word "substantial" interchangeable with "substantive", it jumped out at me that "substantial" has a very different meaning to me, although from the fact that both words are obviously part of the same family, my impression must be incorrect. Anyhow, I think of "substantial" as major and, therefore, a large quantity.
I fully agree that correcting a typo and adding a country to a place name from which it had been missing are not in this category. The addition of the Black Sheep template, however, is the sort of change that I would expect an active profile manager to be consulted about prior to making the change.
With the reflection stimulated by your question, I recognize that "substantive" was probably not a good word choice for this situation.