If you like to update to Factorio version 1.1, here is some code you might need:

-- Research
data.raw["technology"]["artillery"].icon = gfx .. "technology/artillery.png";
data.raw["technology"]["artillery"].icon_size = 128;
data.raw["technology"]["artillery-shell-range-1"].icon = gfx .. "technology/artillery-range.png";
data.raw["technology"]["artillery-shell-range-1"].icon_size = 128;
data.raw["technology"]["artillery-shell-speed-1"].icon = gfx .. "technology/artillery-speed.png";
data.raw["technology"]["artillery-shell-speed-1"].icon_size = 128;

Btw, I just added this mod as dependency to my Christmas Candy Factory.

Yeah that makes sense that the icons changed if they made new ones, I had some icon shifts between 0.18 to 1.0 too.

p.s. cool mod :)

I've just released a 1.1 compatible version, thanks!