I do not know how to check the tags you are referring to.
However, looking over the VS2017 code, it does not feel incomplete compared to the end of the SVN.
I know that is not a scientific comparison.
However, other than changes for Eigen and some other minor stuff, the code has the same basic look and feel.
If you find functionality that is missing, I can add it back in, at least I believe I can anyway.
In the mean time, I am going to go back to work on my own fork.
Adding such things as looking stars etc up by Ra/Dec/Dist.
I use that to illustrate 3D to students.
Watching them as an arc of stars matching a single degree are highlighted in turn is fun.
I made a script that marks all stars from 0-359 degrees, (all Decs/Dists) one degree at a time for visualization.
Then it does the same starting at 0 for Dec (All Ra/Dists), doing 1/-1, and so forth to 180.
And finally it selects a group of stars based on being within a degree of some setting, and marks them.
Then it turns sideways, and backs away to show how the stars are arranged in 3d space.
To me, this is the sort of thing Celestia is great at.
P.S. Your O'Neill colony link in your signature is broken.
As is the lagrange points, which should point here now. https://celestia.space/forum/viewtopic.php?f=23&t=17129