I recently downloaded this mod to save some space by downsizing e-furnaces a bit.
What I did not expect was that the textures were still the same just the collision box has been shrunk to fit in 2x2 spaces.(Possible fix: setting scaling of all textures from 0.5 to 0.3) And also the texture for furnaces in the mod-zip file isn't used.
I also noticed that the crafting speed has been increased to 3 which makes sense in the case of tier based furnaces, first stone then steel then electric, but in vanilla steel and electric are both speed 2. (Possible "fix": setting it back to 2) But this one is more like something of preference than anything else.

I suggest using mini machines (located here). You can disable all of the other mini machines if you only want the mini furnaces.

I've modified each layers within entities.lua as like this

  layers = {
  {
    filename = "__base__/graphics/entity/electric-furnace/electric-furnace-base.png",
    priority = "high",
    width = 129,
    height = 100,
    frame_count = 1,
    shift = {0.421875*0.66, 0*0.66},  -- modi : mul 0.66
    scale = 0.66,     -- modi: append this line
    hr_version = {
      filename = "__base__/graphics/entity/electric-furnace/hr-electric-furnace.png",
      priority = "high",
      width = 239,
      height = 219,
      frame_count = 1,
      shift = util.by_pixel(0.75*0.66, 5.75*0.66),   -- modi : mul 0.66
      scale = 0.5*0.66       -- modi : mul 0.66
    }
  },

It worked well.