Great stuff @dfay!
Note that it's not necessary to hardcode in hacks for these apps that now support Dark Mode natively:
* Things 3.7
* OmniFocus 3.1
* TaskPaper 3.8
* HazeOver 1.8
* Ulysses 14
Hopefully all other apps worth their salt ASAP! However, I must say conflicting times, and I personally want on a per app basis, the abililty to control Dark Mode theme support. So I may be returning to your script enhancements to override the other way soon!