One bug, one thing that you may or may not want:

1. (the bug): In one of your nested-results, you have projectile = "atomic-bomb-wave", instead of what I suspect you meant projectile = "atomic-artillery-wave", (the former is the normal nuclear bomb's AoE damage pulse, the latter is the one you defined in projectiles.lua, but then never use?)

2. (optional/FYI) You can make this mod behave (more) correctly with artillery auto-target if you change how the initial damage pulse is calculated. Right now, it thinks that the true AoE of the round is radius 9, but that's only your destroy-cliffs pulse. I went ahead and did some testing; whatever the first 'radius' value in 'action' is, that's the radius the game assumes the rest of the weapon has. So if you simply move the 'projectile = "atomic-bomb-wave"' nested-result above the destroy-cliffs action, then the game will correctly place shots 35 units apart (center to center). It's still not an ideal shot placement, but the default targeting AI isn't exactly brilliant.

I can submit a PR on github, but because I'd have to do a git-mv to update the version of the folder, the PR would be a huge clusterfuck to read, since every file would be counted as 'everything changed'. :(

I've removed the old "atomic-artillery-wave" because it looked pretty terrible, forgot I even had it there, should've removed it when I replaced the old effects.

The only issue that remains now is the bizarre behaviour of trees being destroyed before the wave actually hits them, looks pretty odd.

Well that's the invisible pressure-wave of air crushing them, so it doesn't look odd to me...