[xorcist]

Perens did not propose the term. It had seen some use in the same circles. The document you link to supports this. Perens, Raymond and O'Reilly was probably the largest influencers in spreading it however.

The use you have found by Caldera, which just had become a Linux company at the time, likely precedes this however. I think that falls under "putting the two words together", as it was not an established term at the time.

There is simply no denying that the people around the OSI and related organizations (there were many, but mostly with people in the same circles) popularized the term and give it a specific meaning. Trying to deduce a historical event by cherry picking newsgroup messages is hard. Better to ask anyone who was around Linux related circles at the time. Being 12 at the time is certainly no guarantee of anything, there are many 12-year-olds that know more than adults, especially at the time when there was such a social explosion from the Internet, and many people were just known by their nicknames.

The situation around open source was really interesting as a social commentary at the time. A lot has been written about the connotations around "free" being problematic in English, but there was so much cultural values around the FSF, and my personal feeling (of which I have no proof) was that it was even more important to find a term that the FSF didn't own, thereby taking control over the discourse around permissionless software development which was just getting started at the time.