You bet guys.
In terms of bugs from a few versions back that still repro, better safe than sorry -- I'd rather close your issue as not a problem after verifying that's the case than miss something that is an ongoing problem. Sometimes it's just a "downstream issue," aka something that was caused by a big that is filed and now would not happen anymore. So noting version number of original save is of some help, but not a big deal. More often than not it's still a bug, though. I never get upset about having to close issues that aren't actually an issue, so if I wind up doing that to anyone, please don't feel bad! Better safe than sorry.
On disease customization, the severities of a lot of that stuff will be editable when the custom difficulties are broken out properly. After diplomacy and the endgame are where I want them, the game lobby startup is next on my hitlist. We're getting there, though it's slower than I'd like just because of the scale of revisions. But excellent progress all the same, I feel like.