First off, I'm going to move your post to the NTA forum where it will get more visibility.
If you don't hear back from the community on your issue, you'll need to open a support ticket.
Also, in case you are interested, there is a release candidate for NTA 3.8. See NTA 3.8 Release Candidate Now Available! post for more info.
Unfortunately our products leave something to be desired when it comes to uninstalling. The cleanup script is more for removing database tables that prevent upgrades to later versions as opposed to an exhaustive system. Is this still an issue or did you get what you needed done? If an issue, please open a support case and mention this thread.
By the way, 3.7 is Gen2 which means the only difference between the version is the license file you have applied. So if you are concerned about future upgrades, this shouldn't be an issue.
Once you start talking about registry entries and orphan files, it can get ugly. I believe your best bet would be to contact SolarWinds support for further assistance.
It is fixed. Thank you....