I think that is a great idea and I encourage you to do it. I might even start one for my Reatta. I really like this thread that Dave started. It is the most popular thread on ROJ but things do get lost in it easily and are hard to find later. Information you save in your own thread like you suggested would be much easier for you to find when you need it.
It's funny that the name "Reatta Owners Journal" inspired you to create your own thread. This website was started in a similar way. I have always kept a journal on my home computer of unique maintenance and repair procedures for cars I own. When I bought my Reatta and found the AACA site, I quickly realized that there are a lot things unique to the Reatta that all Reatta owners should know to properly maintain their cars. So instead of putting the information I normally saved on my computer I created this website in 2007 and started putting the information here organized in a way that other Reatta owners could easily find it. I knew that a lot of the information I put on here would be based on posts on the AACA site so asked them for, and was given, permission to copy posts from that website and save them here as How-to guides.
Later on I added this forum because I was getting so many emails each day from people with questions about their Reatta. It is much easier to answer questions here in the forum so now I just direct people who send me emails here to the forum to get answers to their questions instead of exchanging emails. This is probably more information than you were looking for but now you know the story of how ROJ got started.